Наверняка многие из вас сталкивались с ситуацией, когда браузер отказывается загружать определенную страницу в Интернете, выводя вместо нее сообщение о некоей «Ошибке 404». Реакцию пользователей на такое сообщение можно охарактеризовать по-разному: к нему относятся отрицательно или равнодушно, его боятся или попросту игнорируют. Между тем далеко не каждый знает о том, что в честь этой ошибки создаются целые Интернет-проекты и каталоги ресурсов, проводятся конкурсы и созтязания.
Ошибками в протоколе HTTP называется такое поведение веб-сервера, когда он по какой-то причине не может успешно отправить клиенту запрашиваемый документ. Сервер сообщает клиенту в HTTP-заголовке код ошибки, который на стороне клиента так или иначе интерпретируется браузером.
Каждая ошибка, выдаваемая веб-сервером, имеет код соответствующий классу возникшей ошибки. Коды ошибок (например 403 или 404) стандартизованы и подробно описаны в интернет-стандарте RFC2616 (Hypertext Transfer Protocol — HTTP/1.1). Вы можете обращаться к этому документу за подробным описанием конкретной ошибки как в первоисточнику.
Коды ошибок бывают положительными и отрицательными или успешными и неуспешными. Есть четыре типа кодов:
2xx – запрос выполнен успешно – сервер успешно отправил клиенту запрашиваемый документ
3xx – запрос успешно перенаправлен – тоже положительный код. Он говорит о том, что запрос клиента был перенаправлен. Используется при работе с кэширующими серверами, а также в алгоритме, когда браузер клиента проверяет актуальность документа на сервере (дату создания, размер и так далее)
4xx – ошибка – документ не был отправлен клиенту, так как произошла критическая ошибка. Например, запрошенный документ не найден на сервере, доступ к документу запрещен и так далее и сайт не будет открываться или будет ошибка 404.
5xx – ошибка сервера – критическая ошибка на сервере. Например, на сервере не смог нормально отработать скрипт пользователя
Возможные ошибки при первичном размещении сайта
Содержание статьи
- 1 Возможные ошибки при первичном размещении сайта
- 2 ошибка 403 “Доступ запрещен” – как устранить причины
- 3 обработка ошибки 404 “Файл не найден”
- 4 ошибка 500 “Internal Server Error”
- 5 Рекомендации по созданию страницы ошибки 404
Вы разместили сайт на хостинге компании yutex, загрузили файлы и получили ошибку 403 при попытке открыть сайт через браузер. Эта ошибка возникает в случае если вы назвали индексный файл, который должен показываться при обращении к каталогу, неправильно. Индексный файл может иметь названия index.html, index.htm, index.php, index.phtml, index.shtml, default.htm или default.html. В Unix-системах регистр букв в названиях файлов имеет значение.
ошибка 403 “Доступ запрещен” – как устранить причины
Данная ошибка возникает когда сервер не смог обработать запрос по причине того, что доступ к файлу был запрещен. Наиболее часто это возникает в трех случаях:
— в каталоге нет индексного файла (index.html, например) и при этом запрещен просмотр списка файлов в данном каталоге* или на всем виртуальном сервере. Можно попробовать создать файл с именем index.html и посмотреть не исчезнет ли ошибка.
— выставлены такие “права” доступа на файл, что веб-сервер Apache не смог прочитать файл на диске сервера. Попробуйте изменить права доступа на 640, например.
— пользователь попытался обратиться к скрипту (в каталоге cgi-bin), на который выставлены неправильные права – нет права на чтение+исполнение (r+x) конкретного скрипта. Измените права на 755.
По умолчанию просмотр списка файлов в каталоге запрещен. Для того, чтобы разрешить вывод списка файлов необходимо создать файл .htaccess, в котором прописать директиву Options +Indexes в виде отдельной строки.
обработка ошибки 404 “Файл не найден”
Прежде всего давайте разберемся, что такое “Ошибка 404” и в каких случаях она возникает. С технической точки зрения, “Ошибка 404” (или Error 404) – это кодовый заголовок статуса протокола HTTP (HyperText Transfer Protocol), который, как известно, является чем-то вроде основы взаимодействия удаленных компьютеров всемирной сети. При обращении браузера к веб-серверу, последний посылает кодовый статус запрашиваемого документа. При корректной обработке этого запроса статус идентичен коду “200 OK”. Однако, пользователь не может видеть подобного сообщения по причине отображения содержания запрошенного веб-сайта в своем браузере. В случае если запрос документа браузером обработан с ошибками, пользователь наблюдает сообщение, имеющее статус “404: Not Found”.
Что же означают эти загадочные цифры – 404? Первая цифра 4 указывает на ошибку программы-клиента, т.е. браузера. В этом случае предполагается, что URL сайта был набран неверно в адресной строке браузера или больше не существует физически на запрошенном сервере. Цифра 0 означает общую ошибку синтаксиса протокола. Наконец, последняя четверка относится к отдельной категории ошибок 40х, которая также включает такие распространенные статусы, как “400: Bad Request” и “401: Unauthorized”.
Ошибка 404 (Файл не найден) возникает когда пользователь запрашивает у веб-сервера документ, которого нет на диске. То есть, когда пользователь запрашивает несуществующий файл. Это наиболее “популярная” из всех ошибок. Вы можете наблюдать возникновение таких ошибок в файле error_log и учитывать это – отслеживать какие документы на сервере “не найдены” и корректировать неправильные ссылки из своих html-документов. Также ссылки на несуществующие документы могут вести с других сайтов.
Для удобства посетителей сайта можно обрабатывать ошибки 404 заменяя стандартные ответы веб-сервера на свои страницы с “человеческим” описанием причины возникновения ошибки и советами что делать в этом случае. Также полезно разместить на такой странице карту вашего сайта или ссылку на поисковую систему.
Как обрабатывать ошибку 404. Создайте в каталоге public_html файл .htaccess и поместите в него следующую инструкцию для веб-сервера Apache:
ErrorDocument 404 /404.html
Затем создайте файл 404.html, в который поместите описание возникшей ошибки и советы о том что “что делать” в этом случае посетителю вашего сайта. Теперь пользователь, который наберет в своем браузере адрес несуществующей страницы, будет автоматически перенаправлен сервером на файл 404.html.
С помощью директивы ErrorDocument можно обрабатывать не только ошибку 404, но и практически все другие ошибки. Например, можно обработать так и ошибку 403, которая упоминается в этом документе выше. О файле .htaccess и его практическом использовании можно почитать тут.
ошибка 500 “Internal Server Error”
Ошибка 500 “Internal Server Error” возникает в случае невозможности запуска скрипта, который вы разместили на сервере, в случае ошибок в скрипте, а также в случае когда вы поместили неправильную инструкцию в файл .htaccess. Этот список причин возникновения ошибки 500 не конечный, есть еще масса причин, по которым может возникнуть ошибка 500. Однако, упомянутые три случая встречаются наиболее часто.
Рассмотрим сначала случай, когда вы поместили некорректную инструкцию в файл .htaccess. Если вы ошиблись в написании названия нужной директивы или параметров к ней.
Веб-сервер укажет вам какую конкретно директиву он посчитал ошибочной – ее нужно будет исправить. В данном случае веб-сервер сообщил что директивы DrectoryIndex он не знает. И действительно – нет директивы DrectoryIndex, есть DirectoryIndex. Имеет место опечатка.
Если ошибка 500 возникает при обращении к скрипту на языке Perl, размещенному в каталоге cgi-bin, нужно проверить права доступа на этот скрипт. Права должны быть 755 (rwxrx-rx). Если это не так, нужно изменить права на 755 командой chmod 755 script.pl в unix shell или воспользоваться для этого FTP. Нужно отдельно отметить – права на скрипты должны быть установлены строго в 755.
Пожалуйста, проверьте правильный ли режим передачи файлов по FTP вы использовали при загрузке скрипта на наш сервер. Все скрипты, равно как и любые другие текстовые файлы, должны передаваться по FTP в текстовом (ASCII) режиме. Если же был использован двоичный (Binary) режим передачи файлов, скрипты наверняка работать не будут.
Если после проверки корректности установленных прав на файл скрипта ошибка не исчезла, нужно изучить последние записи в файле error.log – в него веб-сервер помещает все сообщения об ошибках.
Первое, что нужно сделать если вы получили такую ошибку, это проверить правильно ли скрипт выдает HTTP-заголовки. Каждый скрипт должен сначала печатать строку с указанием соответствующего Content-type и только потом непосредственно то, что увидит пользователь.
Рекомендации по созданию страницы ошибки 404
Содержание
—–Используйте как можно меньше сложных терминологических выражений и специфических, непонятных простому пользователю формулировок. Излагайте суть ситуации просто и понятно.
—–Успокаивайте пользователя и всегда укрепляйте его веру в то, что искомый документ обязательно найдется на вашем сервере.
—–Приводите возможные причины возникновения ошибки (технические рассуждения смело заменяйте на предположение о неверном написании URL и т.п.).
Навигация
—–Всегда указывайте ссылки, ведущие на какой-либо из доступных разделов сайта (первая страница, карта сайта и пр.).
—–Включайте основную навигацию в структуру сообщения об ошибке 404: так пользователю будет проще сориентироваться на вашем сервере.
—–Указывайте свои координаты для связи.
—–По возможности, разместите на странице с сообщением об ошибке форму поиска по сайту.
Оформление
—–Избегайте тяжеловесных, перегруженных графикой, заполненных Flash-анимацией и Java-апплетами страниц с сообщением о “404: Not Found”. Эта страница должна грузиться в считанные секунды.
—–Постарайтесь, чтобы оформление страницы 404 не сильно отличалось от общего дизайна вашего сайта.
Following is a list of the most common HTML error codes.
| Code | Description | Comment |
|---|---|---|
| 100 | Continue | |
| 101 | Switching Protocols | |
| 200 | OK | Action completed successfully |
| 201 | Created |
Success following a POST command |
| 202 | Accepted |
Request has been accepted for processing, but processing has not |
| 203 | Partial Information |
Response to a GET command; indicates that the returned meta |
| 204 | No Content |
Server received the request, but there is no information to send back |
| 205 | Reset Content | |
| 206 | Partial Content |
Requested file was partially sent; usually caused by stopping or |
| 300 | Multiple Choices | |
| 301 | Moved Permanently |
Requested a directory instead of a specific file; the web server |
| 302 | Moved Temporarily | |
| 303 | See Other | |
| 304 | Not Modified |
Cached version of the requested file is the same as the file to |
| 305 | Use Proxy | |
| 400 | Bad Request |
Request had bad syntax or was impossible to fulfill |
| 401 | Unauthorized |
User failed to provide a valid user name/password required for |
| 402 | Payment Required | |
| 403 | Forbidden |
Request does not specify the file name, or the directory or the |
| 404 | Not Found | Requested file was not found |
| 405 | Method Not Allowed | |
| 406 | Not Acceptable | |
| 407 | Proxy Authentication Required | |
| 408 | Request Time-Out | |
| 409 | Conflict | |
| 410 | Gone | |
| 411 | Length Required | |
| 412 | Precondition Failed | |
| 413 | Request Entity Too Large | |
| 414 | Request-URL Too Large | |
| 415 | Unsupported Media Type | |
| 500 | Server Error |
In most cases, this error results from a problem with the code or |
| 501 | Not Implemented |
Server does not support the facility required |
| 502 | Bad Gateway | |
| 503 | Out of Resources |
Server cannot process the request due to a system overload; should |
| 504 | Gateway Time-Out |
Service did not respond within the time frame that the gateway was |
| 505 | HTTP Version Not Supported |
This is usually a cascading error caused by a an undefined entity
reference or use of an unencoded ampersand (&) in an URL or body
text. See the previous message for further details.
✉
Check that you are using a proper syntax for your comments, e.g: <!— comment here —>.
This error may appear if you forget the last «—» to close one comment, therefore including the rest
of the content in your comment.
✉
Did you forget to close a (double) quote mark?
✉
This error may appear if you are using a bad syntax for your comments, such as «<!invalid comment>»
The proper syntax for comments is <!— your comment here —>.
✉
This error may appear when the validator receives an empty document. Please make sure that the document you are uploading is not empty, and report any discrepancy.
✉
You have used character data somewhere it is not permitted to appear.
Mistakes that can cause this error include:
- putting text directly in the body of the document without wrapping
it in a container element (such as a <p>aragraph</p>), or - forgetting to quote an attribute value
(where characters such as «%» and «/» are common, but cannot appear
without surrounding quotes), or - using XHTML-style self-closing tags (such as <meta … />)
in HTML 4.01 or earlier. To fix, remove the extra slash (‘/’)
character. For more information about the reasons for this, see
Empty
elements in SGML, HTML, XML, and XHTML.
✉
The element named above was found in a context where it is not allowed.
This could mean that you have incorrectly nested elements — such as a
«style» element in the «body» section instead of inside «head» — or
two elements that overlap (which is not allowed).
One common cause for this error is the use of XHTML syntax in HTML
documents. Due to HTML’s rules of implicitly closed elements, this error
can create cascading effects. For instance, using XHTML’s «self-closing»
tags for «meta» and «link» in the «head» section of a HTML document may
cause the parser to infer the end of the «head» section and the
beginning of the «body» section (where «link» and «meta» are not
allowed; hence the reported error).
✉
The mentioned element is not allowed to appear in the context in which
you’ve placed it; the other mentioned elements are the only ones that
are both allowed there and can contain the element mentioned.
This might mean that you need a containing element, or possibly that
you’ve forgotten to close a previous element.
One possible cause for this message is that you have attempted to put a
block-level element (such as «<p>» or «<table>») inside an
inline element (such as «<a>», «<span>», or «<font>»).
✉
- You forgot to close a tag, or
- you used something inside this tag that was not allowed, and the validator
is complaining that the tag should be closed before such content can be allowed.
The next message, «start tag was here»
points to the particular instance of the tag in question); the
positional indicator points to where the validator expected you to close the
tag.
✉
This is not an error, but rather a pointer to the start tag of the element
the previous error referred to.
✉
You may have neglected to close an element, or perhaps you meant to
«self-close» an element, that is, ending it with «/>» instead of «>».
✉
This is not an error, but rather a pointer to the start tag of the element
the previous error referred to.
✉
Most likely, you nested tags and closed them in the wrong order. For
example <p><em>…</p> is not acceptable, as <em>
must be closed before <p>. Acceptable nesting is:
<p><em>…</em></p>
Another possibility is that you used an element which requires
a child element that you did not include. Hence the parent element
is «not finished», not complete. For instance, in HTML the <head>
element must contain a <title> child element, lists require
appropriate list items (<ul> and <ol> require <li>;
<dl> requires <dt> and <dd>), and so on.
✉
You have used the element named above in your document, but the
document type you are using does not define an element of that name.
This error is often caused by:
- incorrect use of the «Strict» document type with a document that
uses frames (e.g. you must use the «Frameset» document type to get
the «<frameset>» element), - by using vendor proprietary extensions such as «<spacer>»
or «<marquee>» (this is usually fixed by using CSS to achieve
the desired effect instead). - by using upper-case tags in XHTML (in XHTML attributes and elements
must be all lower-case).
✉
The Validator found an end tag for the above element, but that element is
not currently open. This is often caused by a leftover end tag from an
element that was removed during editing, or by an implicitly closed
element (if you have an error related to an element being used where it
is not allowed, this is almost certainly the case). In the latter case
this error will disappear as soon as you fix the original problem.
If this error occurred in a script section of your document, you should probably
read this FAQ entry.
✉
You have used a character that is not considered a «name character» in an
attribute value. Which characters are considered «name characters» varies
between the different document types, but a good rule of thumb is that
unless the value contains only lower or upper case letters in the
range a-z you must put quotation marks around the value. In fact, unless
you have extreme file size requirements it is a very very good
idea to always put quote marks around your attribute values. It
is never wrong to do so, and very often it is absolutely necessary.
✉
An attribute name (and some attribute values) must start with one of
a restricted set of characters. This error usually indicates that
you have failed to add a closing quotation mark on a previous
attribute value (so the attribute value looks like the start of a
new attribute) or have used an attribute that is not defined
(usually a typo in a common attribute name).
✉
«VI delimiter» is a technical term for the equal sign. This error message
means that the name of an attribute and the equal sign cannot be omitted
when specifying an attribute. A common cause for this error message is
the use of «Attribute Minimization» in document types where it is not allowed,
in XHTML for instance.
How to fix: For attributes such as compact, checked or selected, do not write
e.g <option selected … but rather <option selected=»selected» …
✉
You have used the attribute named above in your document, but the
document type you are using does not support that attribute for this
element. This error is often caused by incorrect use of the «Strict»
document type with a document that uses frames (e.g. you must use
the «Transitional» document type to get the «target» attribute), or
by using vendor proprietary extensions such as «marginheight» (this
is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in
the document type you are using, as an undefined element will have no
supported attributes; in this case, see the element-undefined error
message for further information.
How to fix: check the spelling and case of the element and attribute,
(Remember XHTML is all lower-case) and/or
check that they are both allowed in the chosen document type, and/or
use CSS instead of this attribute. If you received this error when using the
<embed> element to incorporate flash media in a Web page, see the
FAQ item on valid flash.
✉
Have you forgotten the «equal» sign marking the separation
between the attribute and its declared value?
Typical syntax is attribute="value".
✉
You have specified an attribute more than once. Example: Using
the «height» attribute twice on the same
«img» tag.
✉
This error almost always means that you’ve forgotten a closing quote on an attribute value. For instance,
in:
<img src="fred.gif>
<!-- 50 lines of stuff -->
<img src="joe.gif">
The «src» value for the first
<img> is the entire
fifty lines of stuff up to the next double quote, which probably
exceeds the SGML-defined
length limit for HTML
string literals. Note that the position indicator in the error
message points to where the attribute value ended — in
this case, the "joe.gif" line.
✉
The value of an attribute contained something that is not allowed by
the specified syntax for that type of attribute. For instance, the
“selected” attribute must be
either minimized as “selected”
or spelled out in full as “selected="selected"”; the variant
“selected=""” is not allowed.
✉
It is possible that you violated the naming convention for this attribute.
For example, id and name attributes must begin with
a letter, not a digit.
✉
This attribute cannot take a space-separated list of words as a value, but only one word («token»).
This may also be caused by the use of a space for the value of an attribute which does not permit it.
✉
The value of this attribute should be a number, and you probably used a wrong syntax.
✉
It is possible that you violated the naming convention for this attribute.
For example, id and name attributes must begin with
a letter, not a digit.
✉
The attribute given above is required for an element that you’ve used,
but you have omitted it. For instance, in most HTML and XHTML document
types the «type» attribute is required on the «script» element and the
«alt» attribute is required for the «img» element.
Typical values for type are
type="text/css" for <style>
and type="text/javascript" for <script>.
✉
The value of the attribute is defined to be one of a list of possible
values but in the document it contained something that is not allowed
for that type of attribute. For instance, the “selected” attribute must be either
minimized as “selected”
or spelled out in full as “selected="selected"”; a value like
“selected="true"” is not
allowed.
✉
Check that you are using a proper syntax for your comments, e.g: <!— comment here —>.
This error may appear if you forget the last «—» to close one comment, and later open another.
✉
You have used an illegal character in your text.
HTML uses the standard
UNICODE Consortium character repertoire,
and it leaves undefined (among others) 65 character codes (0 to 31 inclusive and 127 to 159
inclusive) that are sometimes used for typographical quote marks and similar in
proprietary character sets. The validator has found one of these undefined
characters in your document. The character may appear on your browser as a
curly quote, or a trademark symbol, or some other fancy glyph; on a different
computer, however, it will likely appear as a completely different
character, or nothing at all.
Your best bet is to replace the character with the nearest equivalent
ASCII character, or to use an appropriate character
entity.
For more information on Character Encoding on the web, see Alan
Flavell’s excellent HTML Character
Set Issues reference.
This error can also be triggered by formatting characters embedded in
documents by some word processors. If you use a word processor to edit
your HTML documents, be sure to use the «Save as ASCII» or similar
command to save the document without formatting information.
✉
An «id» is a unique identifier. Each time this attribute is used in a document
it must have a different value. If you are using this attribute as a hook for
style sheets it may be more appropriate to use classes (which group elements)
than id (which are used to identify exactly one element).
✉
This error can be triggered by:
- A non-existent input, select or textarea element
- A missing id attribute
- A typographical error in the id attribute
Try to check the spelling and case of the id you are referring to.
✉
The document type could not be determined, because the document had no correct DOCTYPE declaration. The document does not look like HTML, therefore automatic fallback could not be performed, and the document was only checked against basic markup syntax.
Learn how to add a doctype to your document
from our FAQ, or use the validator’s
Document Type option to validate your document against a specific Document Type.
✉
The construct <foo<bar> is valid in HTML (it is an example of the rather obscure “Shorttags” feature)
but its use is not recommended.
In most cases, this is a typo that you will want to fix. If you really want to use shorttags,
be aware that they are not well implemented by browsers.
✉
For the current document, the validator interprets strings like
<FOO /> according to legacy rules that
break the expectations of most authors and thus cause confusing warnings
and error messages from the validator. This interpretation is triggered
by HTML 4 documents or other SGML-based HTML documents. To avoid the
messages, simply remove the «/» character in such contexts. NB: If you
expect <FOO /> to be interpreted as an
XML-compatible «self-closing» tag, then you need to use XHTML or HTML5.
This warning and related errors may also be caused by an unquoted
attribute value containing one or more «/». Example:
<a href=http://w3c.org>W3C</a>.
In such cases, the solution is to put quotation marks around the value.
✉
The construct </foo<bar> is valid in HTML (it is an example of the rather obscure “Shorttags” feature)
but its use is not recommended.
In most cases, this is a typo that you will want to fix. If you really want to use shorttags,
be aware that they are not well implemented by browsers.
✉
A DOCTYPE declares the version of the language used, as well as what the root
(top) element of your document will be. For example, if the top element
of your document is <html>, the DOCTYPE declaration
will look like: «<!DOCTYPE html».
In most cases, it is safer not to type or edit the DOCTYPE declaration at all,
and preferable to let a tool include it, or copy and paste it from a
trusted list of DTDs.
✉
This is usually a cascading error caused by a an undefined entity
reference or use of an unencoded ampersand (&) in an URL or body
text. See the previous message for further details.
✉
The construct <> is sometimes valid in HTML (it is an example of the rather obscure “Shorttags” feature)
but its use is not recommended.
In most cases, this is a typo that you will want to fix. If you really want to use shorttags,
be aware that they are not well implemented by browsers.
✉
The construct </> is valid in HTML (it is an example of the rather obscure “Shorttags” feature)
but its use is not recommended.
In most cases, this is a typo that you will want to fix. If you really want to use shorttags,
be aware that they are not well implemented by browsers.
✉
An entity reference was found in the document, but there is no reference
by that name defined. Often this is caused by misspelling the reference
name, unencoded ampersands, or by leaving off the trailing semicolon (;).
The most common cause of this error is unencoded ampersands in
URLs as described by the WDG in «Ampersands
in URLs».
Entity references start with an ampersand (&) and end with a
semicolon (;). If you want to use a literal ampersand in your document
you must encode it as «&» (even inside URLs!). Be
careful to end entity references with a semicolon or your entity
reference may get interpreted in connection with the following text.
Also keep in mind that named entity references are case-sensitive;
&Aelig; and æ are different characters.
If this error appears in some markup generated by PHP’s session handling
code, this article has
explanations and solutions to your problem.
Note that in most documents, errors related to entity references will
trigger up to 5 separate messages from the Validator. Usually these
will all disappear when the original problem is fixed.
✉
The checked page did not contain a document type («DOCTYPE») declaration.
The Validator has tried to validate with a fallback DTD,
but this is quite likely to be incorrect and will generate a large number
of incorrect error messages. It is highly recommended that you insert the
proper DOCTYPE declaration in your document — instructions for doing this
are given above — and it is necessary to have this declaration before the
page can be declared to be valid.
✉
Your document includes a DOCTYPE declaration with a public identifier
(e.g. «-//W3C//DTD XHTML 1.0 Strict//EN») but no system identifier
(e.g. «http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd»). This is
authorized in HTML (based on SGML), but not in XML-based languages.
If you are using a standard XHTML document type, it is recommended to use exactly
one of the DOCTYPE declarations from the
recommended list on the W3C QA Website.
✉
This may happen if you have consecutive comments but did not close one of them properly.
The proper syntax for comments is <!— my comment —>.
✉
If you meant to include an entity that starts with «&», then you should
terminate it with «;». Another reason for this error message is that
you inadvertently created an entity by failing to escape an «&»
character just before this text.
✉
This is generally the sign of an ampersand that was not properly escaped for inclusion
in an attribute, in a href for example. You will need to escape all instances of ‘&’
into ‘&’.
✉
This message may appear in several cases:
- You tried to include the «<» character in your page: you should escape it as «<»
- You used an unescaped ampersand «&»: this may be valid in some contexts,
but it is recommended to use «&», which is always safe. - Another possibility is that you forgot to close quotes in a previous tag.
✉
This error may occur when there is a mistake in how a self-closing tag is closed, e.g ‘…/ >’.
The proper syntax is ‘… />’ (note the position of the space).
✉
You’ve included a character reference to a character that is not defined
in the document type you’ve chosen. This is most commonly caused by
numerical references to characters from vendor proprietary
character repertoires. Often the culprit will be fancy or typographical
quote marks from either the Windows or Macintosh character repertoires.
The solution is to reference UNICODE characters instead. A list of
common characters from the Windows character repertoire and their
UNICODE equivalents can be found in the document «On the use of some MS Windows characters in HTML» maintained by
Jukka Korpela
<jkorpela@cs.tut.fi>.
✉
The following validation errors do not have an explanation yet. We invite you to use the
feedback channels to send your suggestions.
0: length of name must not exceed NAMELEN (X)
✉
1: length of parameter entity name must not exceed NAMELEN less the length of the PERO delimiter (X)
✉
2: length of number must not exceed NAMELEN (X)
✉
3: length of attribute value must not exceed LITLEN less NORMSEP (X)
✉
4: a name group is not allowed in a parameter entity reference in the prolog
✉
5: an entity end in a token separator must terminate an entity referenced in the same group
✉
6: character X invalid: only Y and token separators allowed
✉
7: a parameter separator is required after a number that is followed by a name start character
✉
8: character X invalid: only Y and parameter separators allowed
✉
9: an entity end in a parameter separator must terminate an entity referenced in the same declaration
✉
10: an entity end is not allowed in a token separator that does not follow a token
✉
11: X is not a valid token here
✉
12: a parameter entity reference can only occur in a group where a token could occur
✉
13: token X has already occurred in this group
✉
14: the number of tokens in a group must not exceed GRPCNT (X)
✉
15: an entity end in a literal must terminate an entity referenced in the same literal
✉
16: character X invalid: only minimum data characters allowed
✉
18: a parameter literal in a data tag pattern must not contain a numeric character reference to a non-SGML character
✉
19: a parameter literal in a data tag pattern must not contain a numeric character reference to a function character
✉
20: a name group is not allowed in a general entity reference in a start tag
✉
21: a name group is not allowed in a general entity reference in the prolog
✉
22: X is not a function name
✉
23: X is not a character number in the document character set
✉
24: parameter entity X not defined
✉
26: RNI delimiter must be followed by name start character
✉
29: comment started here
✉
30: only one type of connector should be used in a single group
✉
31: X is not a reserved name
✉
32: X is not allowed as a reserved name here
✉
33: length of interpreted minimum literal must not exceed reference LITLEN (X)
✉
34: length of tokenized attribute value must not exceed LITLEN less NORMSEP (X)
✉
35: length of system identifier must not exceed LITLEN (X)
✉
36: length of interpreted parameter literal must not exceed LITLEN (X)
✉
37: length of interpreted parameter literal in data tag pattern must not exceed DTEMPLEN (X)
✉
39: X invalid: only Y and parameter separators are allowed
✉
40: X invalid: only Y and token separators are allowed
✉
41: X invalid: only Y and token separators are allowed
✉
43: X declaration not allowed in DTD subset
✉
44: character X not allowed in declaration subset
✉
45: end of document in DTD subset
✉
46: character X not allowed in prolog
✉
48: X declaration not allowed in prolog
✉
49: X used both a rank stem and generic identifier
✉
50: omitted tag minimization parameter can be omitted only if OMITTAG NO is specified
✉
51: element type X already defined
✉
52: entity reference with no applicable DTD
✉
53: invalid comment declaration: found X outside comment but inside comment declaration
✉
54: comment declaration started here
✉
55: X declaration not allowed in instance
✉
56: non-SGML character not allowed in content
✉
57: no current rank for rank stem X
✉
58: duplicate attribute definition list for notation X
✉
59: duplicate attribute definition list for element X
✉
60: entity end not allowed in end tag
✉
61: character X not allowed in end tag
✉
62: X invalid: only S separators and TAGC allowed here
✉
66: document type does not allow element X here; assuming missing Y start-tag
✉
67: no start tag specified for implied empty element X
✉
72: start tag omitted for element X with declared content
✉
74: start tag for X omitted, but its declaration does not permit this
✉
75: number of open elements exceeds TAGLVL (X)
✉
77: empty end tag but no open elements
✉
78: X not finished but containing element ended
✉
80: internal parameter entity X cannot be CDATA or SDATA
✉
81: character X not allowed in attribute specification list
✉
83: entity end not allowed in attribute specification list except in attribute value literal
✉
84: external parameter entity X cannot be CDATA, SDATA, NDATA or SUBDOC
✉
85: duplicate declaration of entity X
✉
86: duplicate declaration of parameter entity X
✉
87: a reference to a PI entity is allowed only in a context where a processing instruction could occur
✉
88: a reference to a CDATA or SDATA entity is allowed only in a context where a data character could occur
✉
89: a reference to a subdocument entity or external data entity is allowed only in a context where a data character could occur
✉
90: a reference to a subdocument entity or external data entity is not allowed in replaceable character data
✉
91: the number of open entities cannot exceed ENTLVL (X)
✉
92: a reference to a PI entity is not allowed in replaceable character data
✉
93: entity X is already open
✉
94: short reference map X not defined
✉
95: short reference map in DTD must specify associated element type
✉
96: short reference map in document instance cannot specify associated element type
✉
97: short reference map X for element Y not defined in DTD
✉
98: X is not a short reference delimiter
✉
99: short reference delimiter X already mapped in this declaration
✉
100: no document element
✉
102: entity end not allowed in processing instruction
✉
103: length of processing instruction must not exceed PILEN (X)
✉
104: missing PIC delimiter
✉
106: X is not a member of a group specified for any attribute
✉
109: an attribute value specification must start with a literal or a name character
✉
110: length of name token must not exceed NAMELEN (X)
✉
113: duplicate definition of attribute X
✉
114: data attribute specification must be omitted if attribute specification list is empty
✉
115: marked section end not in marked section declaration
✉
116: number of open marked sections must not exceed TAGLVL (X)
✉
117: missing marked section end
✉
118: marked section started here
✉
119: entity end in character data, replaceable character data or ignored marked section
✉
126: non-impliable attribute X not specified but OMITTAG NO and SHORTTAG NO
✉
128: first occurrence of CURRENT attribute X not specified
✉
129: X is not a notation name
✉
130: X is not a general entity name
✉
132: X is not a data or subdocument entity
✉
133: content model is ambiguous: when no tokens have been matched, both the Y and Z occurrences of X are possible
✉
134: content model is ambiguous: when the current token is the Y occurrence of X, both the a and b occurrences of Z are possible
✉
135: content model is ambiguous: when the current token is the Y occurrence of X and the innermost containing AND group has been matched, both the a and b occurrences of Z are possible
✉
136: content model is ambiguous: when the current token is the Y occurrence of X and the innermost Z containing AND groups have been matched, both the b and c occurrences of a are possible
✉
138: comment declaration started here
✉
140: data or replaceable character data in declaration subset
✉
142: ID X first defined here
✉
143: value of fixed attribute X not equal to default
✉
144: character X is not significant in the reference concrete syntax and so cannot occur in a comment in the SGML declaration
✉
145: minimum data of first minimum literal in SGML declaration must be «»ISO 8879:1986″» or «»ISO 8879:1986 (ENR)»» or «»ISO 8879:1986 (WWW)»» not X
✉
146: parameter before LCNMSTRT must be NAMING not X
✉
147: unexpected entity end in SGML declaration: only X, S separators and comments allowed
✉
148: X invalid: only Y and parameter separators allowed
✉
149: magnitude of X too big
✉
150: character X is not significant in the reference concrete syntax and so cannot occur in a literal in the SGML declaration except as the replacement of a character reference
✉
151: X is not a valid syntax reference character number
✉
152: a parameter entity reference cannot occur in an SGML declaration
✉
153: X invalid: only Y and parameter separators are allowed
✉
154: cannot continue because of previous errors
✉
155: SGML declaration cannot be parsed because the character set does not contain characters having the following numbers in ISO 646: X
✉
156: the specified character set is invalid because it does not contain the minimum data characters having the following numbers in ISO 646: X
✉
157: character numbers declared more than once: X
✉
158: character numbers should have been declared UNUSED: X
✉
159: character numbers missing in base set: X
✉
160: characters in the document character set with numbers exceeding X not supported
✉
161: invalid formal public identifier X: missing //
✉
162: invalid formal public identifier X: no SPACE after public text class
✉
163: invalid formal public identifier X: invalid public text class
✉
164: invalid formal public identifier X: public text language must be a name containing only upper case letters
✉
165: invalid formal public identifer X: public text display version not permitted with this text class
✉
166: invalid formal public identifier X: extra field
✉
167: public text class of public identifier in notation identifier must be NOTATION
✉
168: base character set X is unknown
✉
169: delimiter set is ambiguous: X and Y can be recognized in the same mode
✉
170: characters with the following numbers in the syntax reference character set are significant in the concrete syntax but are not in the document character set: X
✉
171: there is no unique character in the document character set corresponding to character number X in the syntax reference character set
✉
172: there is no unique character in the internal character set corresponding to character number X in the syntax reference character set
✉
173: the character with number X in ISO 646 is significant but has no representation in the syntax reference character set
✉
174: capacity set X is unknown
✉
175: capacity X already specified
✉
176: value of capacity X exceeds value of TOTALCAP
✉
177: syntax X is unknown
✉
178: UCNMSTRT must have the same number of characters as LCNMSTRT
✉
179: UCNMCHAR must have the same number of characters as LCNMCHAR
✉
180: number of open subdocuments exceeds quantity specified for SUBDOC parameter in SGML declaration (X)
✉
181: entity X declared SUBDOC, but SUBDOC NO specified in SGML declaration
✉
182: a parameter entity referenced in a parameter separator must end in the same declaration
✉
184: generic identifier X used in DTD but not defined
✉
185: X not finished but document ended
✉
186: cannot continue with subdocument because of previous errors
✉
188: no internal or external document type declaration subset; will parse without validation
✉
189: this is not an SGML document
✉
190: length of start-tag before interpretation of literals must not exceed TAGLEN (X)
✉
191: a parameter entity referenced in a token separator must end in the same group
✉
192: the following character numbers are shunned characters that are not significant and so should have been declared UNUSED: X
✉
193: there is no unique character in the specified document character set corresponding to character number X in ISO 646
✉
194: length of attribute value must not exceed LITLEN less NORMSEP (-X)
✉
195: length of tokenized attribute value must not exceed LITLEN less NORMSEP (-X)
✉
196: concrete syntax scope is INSTANCE but value of X quantity is less than value in reference quantity set
✉
197: public text class of formal public identifier of base character set must be CHARSET
✉
198: public text class of formal public identifier of capacity set must be CAPACITY
✉
199: public text class of formal public identifier of concrete syntax must be SYNTAX
✉
200: when there is an MSOCHAR there must also be an MSICHAR
✉
201: character number X in the syntax reference character set was specified as a character to be switched but is not a markup character
✉
202: character number X was specified as a character to be switched but is not in the syntax reference character set
✉
203: character numbers X in the document character set have been assigned the same meaning, but this is the meaning of a significant character
✉
204: character number X assigned to more than one function
✉
205: X is already a function name
✉
206: characters with the following numbers in ISO 646 are significant in the concrete syntax but are not in the document character set: X
✉
207: general delimiter X consists solely of function characters
✉
208: letters assigned to LCNMCHAR, UCNMCHAR, LCNMSTRT or UCNMSTRT: X
✉
209: digits assigned to LCNMCHAR, UCNMCHAR, LCNMSTRT or UCNMSTRT: X
✉
210: character number X cannot be assigned to LCNMCHAR, UCNMCHAR, LCNMSTRT or UCNMSTRT because it is RE
✉
211: character number X cannot be assigned to LCNMCHAR, UCNMCHAR, LCNMSTRT or UCNMSTRT because it is RS
✉
212: character number X cannot be assigned to LCNMCHAR, UCNMCHAR, LCNMSTRT or UCNMSTRT because it is SPACE
✉
213: separator characters assigned to LCNMCHAR, UCNMCHAR, LCNMSTRT or UCNMSTRT: X
✉
214: character number X cannot be switched because it is a Digit, LC Letter or UC Letter
✉
215: pointless for number of characters to be 0
✉
216: X cannot be the replacement for a reference reserved name because it is another reference reserved name
✉
217: X cannot be the replacement for a reference reserved name because it is the replacement of another reference reserved name
✉
218: replacement for reserved name X already specified
✉
219: X is not a valid name in the declared concrete syntax
✉
220: X is not a valid short reference delimiter because it has more than one B sequence
✉
221: X is not a valid short reference delimiter because it is adjacent to a character that can occur in a blank sequence
✉
222: length of delimiter X exceeds NAMELEN (Y)
✉
223: length of reserved name X exceeds NAMELEN (Y)
✉
224: character numbers assigned to both LCNMCHAR or UCNMCHAR and LCNMSTRT or UCNMSTRT: X
✉
225: when the concrete syntax scope is INSTANCE the syntax reference character set of the declared syntax must be the same as that of the reference concrete syntax
✉
226: end-tag minimization should be O for element with declared content of EMPTY
✉
227: end-tag minimization should be O for element X because it has CONREF attribute
✉
228: element X has a declared content of EMPTY and a CONREF attribute
✉
229: element X has a declared content of EMPTY and a NOTATION attribute
✉
230: declared value of data attribute cannot be ENTITY, ENTITIES, ID, IDREF, IDREFS or NOTATION
✉
231: default value of data attribute cannot be CONREF or CURRENT
✉
232: number of attribute names and name tokens (X) exceeds ATTCNT (Y)
✉
233: if the declared value is ID the default value must be IMPLIED or REQUIRED
✉
234: the attribute definition list already declared attribute X as the ID attribute
✉
235: the attribute definition list already declared attribute X as the NOTATION attribute
✉
236: token X occurs more than once in attribute definition list
✉
237: no attributes defined for notation X
✉
238: notation X for entity Y undefined
✉
239: entity X undefined in short reference map Y
✉
240: notation X is undefined but had attribute definition
✉
241: length of interpreted parameter literal in bracketed text plus the length of the bracketing delimiters must not exceed LITLEN (X)
✉
242: length of rank stem plus length of rank suffix must not exceed NAMELEN (X)
✉
243: document instance must start with document element
✉
244: content model nesting level exceeds GRPLVL (X)
✉
245: grand total of content tokens exceeds GRPGTCNT (X)
✉
249: DTDs other than base allowed only if CONCUR YES or EXPLICIT YES
✉
250: end of entity other than document entity after document element
✉
251: X declaration illegal after document element
✉
252: character reference illegal after document element
✉
253: entity reference illegal after document element
✉
254: marked section illegal after document element
✉
255: the X occurrence of Y in the content model for Z cannot be excluded at this point because it is contextually required
✉
256: the X occurrence of Y in the content model for Z cannot be excluded because it is neither inherently optional nor a member of an OR group
✉
257: an attribute value specification must be an attribute value literal unless SHORTTAG YES is specified
✉
258: value cannot be specified both for notation attribute and content reference attribute
✉
259: notation X already defined
✉
260: short reference map X already defined
✉
261: first defined here
✉
262: general delimiter role X already defined
✉
263: number of ID references in start-tag must not exceed GRPCNT (X)
✉
264: number of entity names in attribute specification list must not exceed GRPCNT (X)
✉
265: normalized length of attribute specification list must not exceed ATTSPLEN (X); length was Y
✉
266: short reference delimiter X already specified
✉
267: single character short references were already specified for character numbers: X
✉
268: default entity used in entity attribute X
✉
269: reference to entity X uses default entity
✉
270: entity X in short reference map Y uses default entity
✉
271: no DTD X declared
✉
272: LPD X has neither internal nor external subset
✉
273: element types have different link attribute definitions
✉
274: link set X already defined
✉
275: empty result attribute specification
✉
276: no source element type X
✉
277: no result element type X
✉
278: end of document in LPD subset
✉
279: X declaration not allowed in LPD subset
✉
280: ID link set declaration not allowed in simple link declaration subset
✉
281: link set declaration not allowed in simple link declaration subset
✉
282: attributes can only be defined for base document element (not X) in simple link declaration subset
✉
283: a short reference mapping declaration is allowed only in the base DTD
✉
284: a short reference use declaration is allowed only in the base DTD
✉
285: default value of link attribute cannot be CURRENT or CONREF
✉
286: declared value of link attribute cannot be ID, IDREF, IDREFS or NOTATION
✉
287: only fixed attributes can be defined in simple LPD
✉
288: only one ID link set declaration allowed in an LPD subset
✉
289: no initial link set defined for LPD X
✉
290: notation X not defined in source DTD
✉
291: result document type in simple link specification must be implied
✉
292: simple link requires SIMPLE YES
✉
293: implicit link requires IMPLICIT YES
✉
294: explicit link requires EXPLICIT YES
✉
295: LPD not allowed before first DTD
✉
296: DTD not allowed after an LPD
✉
297: definition of general entity X is unstable
✉
298: definition of parameter entity X is unstable
✉
299: multiple link rules for ID X but not all have link attribute specifications
✉
300: multiple link rules for element type X but not all have link attribute specifications
✉
301: link type X does not have a link set Y
✉
302: link set use declaration for simple link process
✉
303: no link type X
✉
304: both document type and link type X
✉
305: link type X already defined
✉
306: document type X already defined
✉
307: link set X used in LPD but not defined
✉
308: #IMPLIED already linked to result element type X
✉
309: number of active simple link processes exceeds quantity specified for SIMPLE parameter in SGML declaration (X)
✉
310: only one chain of explicit link processes can be active
✉
311: source document type name for link type X must be base document type since EXPLICIT YES 1
✉
312: only one implicit link process can be active
✉
313: sorry, link type X not activated: only one implicit or explicit link process can be active (with base document type as source document type)
✉
314: name missing after name group in entity reference
✉
315: source document type name for link type X must be base document type since EXPLICIT NO
✉
316: link process must be activated before base DTD
✉
317: unexpected entity end while starting second pass
✉
318: type X of element with ID Y not associated element type for applicable link rule in ID link set
✉
319: DATATAG feature not implemented
✉
320: generic identifier specification missing after document type specification in start-tag
✉
321: generic identifier specification missing after document type specification in end-tag
✉
322: a NET-enabling start-tag cannot include a document type specification
✉
324: invalid default SGML declaration
✉
326: entity was defined here
✉
327: content model is mixed but does not allow #PCDATA everywhere
✉
328: start or end of range must specify a single character
✉
329: number of first character in range must not exceed number of second character in range
✉
330: delimiter cannot be an empty string
✉
331: too many characters assigned same meaning with minimum literal
✉
332: earlier reference to entity X used default entity
✉
335: unused short reference map X
✉
336: unused parameter entity X
✉
337: cannot generate system identifier for public text X
✉
339: cannot generate system identifier for parameter entity X
✉
340: cannot generate system identifier for document type X
✉
341: cannot generate system identifier for link type X
✉
342: cannot generate system identifier for notation X
✉
343: element type X both included and excluded
✉
345: minimum data of AFDR declaration must be «»ISO/IEC 10744:1997″» not X
✉
346: AFDR declaration required before use of AFDR extensions
✉
347: ENR extensions were used but minimum literal was not «»ISO 8879:1986 (ENR)»» or «»ISO 8879:1986 (WWW)»»
✉
348: illegal numeric character reference to non-SGML character X in literal
✉
349: cannot convert character reference to number X because description Y unrecognized
✉
350: cannot convert character reference to number X because character Y from baseset Z unknown
✉
351: character reference to number X cannot be converted because of problem with internal character set
✉
352: cannot convert character reference to number X because character not in internal character set
✉
353: Web SGML adaptations were used but minimum literal was not «»ISO 8879:1986 (WWW)»»
✉
354: token X can be value for multiple attributes so attribute name required
✉
355: length of hex number must not exceed NAMELEN (X)
✉
356: X is not a valid name in the declared concrete syntax
✉
357: CDATA declared content
✉
358: RCDATA declared content
✉
359: inclusion
✉
360: exclusion
✉
361: NUMBER or NUMBERS declared value
✉
362: NAME or NAMES declared value
✉
363: NUTOKEN or NUTOKENS declared value
✉
364: CONREF attribute
✉
365: CURRENT attribute
✉
366: TEMP marked section
✉
367: included marked section in the instance
✉
368: ignored marked section in the instance
✉
369: RCDATA marked section
✉
370: processing instruction entity
✉
371: bracketed text entity
✉
372: internal CDATA entity
✉
373: internal SDATA entity
✉
374: external CDATA entity
✉
375: external SDATA entity
✉
376: attribute definition list declaration for notation
✉
377: rank stem
✉
379: comment in parameter separator
✉
380: named character reference
✉
381: AND group
✉
382: attribute value not a literal
✉
383: attribute name missing
✉
384: element declaration for group of element types
✉
385: attribute definition list declaration for group of element types
✉
386: empty comment declaration
✉
388: multiple comments in comment declaration
✉
389: no status keyword
✉
390: multiple status keywords
✉
391: parameter entity reference in document instance
✉
392: CURRENT attribute
✉
393: element type minimization parameter
✉
395: #PCDATA not first in model group
✉
396: #PCDATA in SEQ group
✉
397: #PCDATA in nested model group
✉
398: #PCDATA in model group that does not have REP occurrence indicator
✉
399: name group or name token group used connector other than OR
✉
400: processing instruction does not start with name
✉
401: S separator in status keyword specification in document instance
✉
402: reference to external data entity
✉
405: SGML declaration was not implied
✉
406: marked section in internal DTD subset
✉
408: entity end in different element from entity reference
✉
409: NETENABL IMMEDNET requires EMPTYNRM YES
✉
411: declaration of default entity
✉
412: reference to parameter entity in parameter separator in internal subset
✉
413: reference to parameter entity in token separator in internal subset
✉
414: reference to parameter entity in parameter literal in internal subset
✉
415: cannot generate system identifier for SGML declaration reference
✉
416: public text class of formal public identifier of SGML declaration must be SD
✉
417: SGML declaration reference was used but minimum literal was not «»ISO 8879:1986 (WWW)»»
✉
418: member of model group containing #PCDATA has occurrence indicator
✉
419: member of model group containing #PCDATA is a model group
✉
420: reference to non-predefined entity
✉
421: reference to external entity
✉
422: declaration of default entity conflicts with IMPLYDEF ENTITY YES
✉
423: parsing with respect to more than one active doctype not supported
✉
424: cannot have active doctypes and link types at the same time
✉
425: number of concurrent document instances exceeds quantity specified for CONCUR parameter in SGML declaration (X)
✉
426: datatag group can only be specified in base document type
✉
427: element not in the base document type can’t have an empty start-tag
✉
428: element not in base document type can’t have an empty end-tag
✉
429: immediately recursive element
✉
430: invalid URN X: missing «»:»»
✉
431: invalid URN X: missing «»urn:»» prefix
✉
432: invalid URN X: invalid namespace identifier
✉
433: invalid URN X: invalid namespace specific string
✉
434: invalid URN X: extra field
✉
435: prolog can’t be omitted unless CONCUR NO and LINK EXPLICIT NO and either IMPLYDEF ELEMENT YES or IMPLYDEF DOCTYPE YES
✉
436: can’t determine name of #IMPLIED document element
✉
437: can’t use #IMPLICIT doctype unless CONCUR NO and LINK EXPLICIT NO
✉
438: Sorry, #IMPLIED doctypes not implemented
✉
439: reference to DTD data entity ignored
✉
440: notation X for parameter entity Y undefined
✉
441: notation X for external subset undefined
✉
442: attribute X can’t be redeclared
✉
443: #IMPLICIT attributes have already been specified for notation X
✉
444: a name group is not allowed in a parameter entity reference in a start tag
✉
445: name group in a parameter entity reference in an end tag (SGML forbids them in start tags)
✉
446: if the declared value is NOTATION a default value of CONREF is useless
✉
447: Sorry, #ALL and #IMPLICIT content tokens not implemented
✉
From Wikipedia, the free encyclopedia
This is a list of Hypertext Transfer Protocol (HTTP) response status codes. Status codes are issued by a server in response to a client’s request made to the server. It includes codes from IETF Request for Comments (RFCs), other specifications, and some additional codes used in some common applications of the HTTP. The first digit of the status code specifies one of five standard classes of responses. The optional message phrases shown are typical, but any human-readable alternative may be provided, or none at all.
Unless otherwise stated, the status code is part of the HTTP standard (RFC 9110).
The Internet Assigned Numbers Authority (IANA) maintains the official registry of HTTP status codes.[1]
All HTTP response status codes are separated into five classes or categories. The first digit of the status code defines the class of response, while the last two digits do not have any classifying or categorization role. There are five classes defined by the standard:
- 1xx informational response – the request was received, continuing process
- 2xx successful – the request was successfully received, understood, and accepted
- 3xx redirection – further action needs to be taken in order to complete the request
- 4xx client error – the request contains bad syntax or cannot be fulfilled
- 5xx server error – the server failed to fulfil an apparently valid request
1xx informational response
An informational response indicates that the request was received and understood. It is issued on a provisional basis while request processing continues. It alerts the client to wait for a final response. The message consists only of the status line and optional header fields, and is terminated by an empty line. As the HTTP/1.0 standard did not define any 1xx status codes, servers must not[note 1] send a 1xx response to an HTTP/1.0 compliant client except under experimental conditions.
- 100 Continue
- The server has received the request headers and the client should proceed to send the request body (in the case of a request for which a body needs to be sent; for example, a POST request). Sending a large request body to a server after a request has been rejected for inappropriate headers would be inefficient. To have a server check the request’s headers, a client must send
Expect: 100-continueas a header in its initial request and receive a100 Continuestatus code in response before sending the body. If the client receives an error code such as 403 (Forbidden) or 405 (Method Not Allowed) then it should not send the request’s body. The response417 Expectation Failedindicates that the request should be repeated without theExpectheader as it indicates that the server does not support expectations (this is the case, for example, of HTTP/1.0 servers).[2] - 101 Switching Protocols
- The requester has asked the server to switch protocols and the server has agreed to do so.
- 102 Processing (WebDAV; RFC 2518)
- A WebDAV request may contain many sub-requests involving file operations, requiring a long time to complete the request. This code indicates that the server has received and is processing the request, but no response is available yet.[3] This prevents the client from timing out and assuming the request was lost. The status code is deprecated.[4]
- 103 Early Hints (RFC 8297)
- Used to return some response headers before final HTTP message.[5]
2xx success
This class of status codes indicates the action requested by the client was received, understood, and accepted.[1]
- 200 OK
- Standard response for successful HTTP requests. The actual response will depend on the request method used. In a GET request, the response will contain an entity corresponding to the requested resource. In a POST request, the response will contain an entity describing or containing the result of the action.
- 201 Created
- The request has been fulfilled, resulting in the creation of a new resource.[6]
- 202 Accepted
- The request has been accepted for processing, but the processing has not been completed. The request might or might not be eventually acted upon, and may be disallowed when processing occurs.
- 203 Non-Authoritative Information (since HTTP/1.1)
- The server is a transforming proxy (e.g. a Web accelerator) that received a 200 OK from its origin, but is returning a modified version of the origin’s response.[7][8]
- 204 No Content
- The server successfully processed the request, and is not returning any content.
- 205 Reset Content
- The server successfully processed the request, asks that the requester reset its document view, and is not returning any content.
- 206 Partial Content
- The server is delivering only part of the resource (byte serving) due to a range header sent by the client. The range header is used by HTTP clients to enable resuming of interrupted downloads, or split a download into multiple simultaneous streams.
- 207 Multi-Status (WebDAV; RFC 4918)
- The message body that follows is by default an XML message and can contain a number of separate response codes, depending on how many sub-requests were made.[9]
- 208 Already Reported (WebDAV; RFC 5842)
- The members of a DAV binding have already been enumerated in a preceding part of the (multistatus) response, and are not being included again.
- 226 IM Used (RFC 3229)
- The server has fulfilled a request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.[10]
3xx redirection
This class of status code indicates the client must take additional action to complete the request. Many of these status codes are used in URL redirection.[1]
A user agent may carry out the additional action with no user interaction only if the method used in the second request is GET or HEAD. A user agent may automatically redirect a request. A user agent should detect and intervene to prevent cyclical redirects.[11]
- 300 Multiple Choices
- Indicates multiple options for the resource from which the client may choose (via agent-driven content negotiation). For example, this code could be used to present multiple video format options, to list files with different filename extensions, or to suggest word-sense disambiguation.
- 301 Moved Permanently
- This and all future requests should be directed to the given URI.
- 302 Found (Previously «Moved temporarily»)
- Tells the client to look at (browse to) another URL. The HTTP/1.0 specification (RFC 1945) required the client to perform a temporary redirect with the same method (the original describing phrase was «Moved Temporarily»),[12] but popular browsers implemented 302 redirects by changing the method to GET. Therefore, HTTP/1.1 added status codes 303 and 307 to distinguish between the two behaviours.[11]
- 303 See Other (since HTTP/1.1)
- The response to the request can be found under another URI using the GET method. When received in response to a POST (or PUT/DELETE), the client should presume that the server has received the data and should issue a new GET request to the given URI.
- 304 Not Modified
- Indicates that the resource has not been modified since the version specified by the request headers If-Modified-Since or If-None-Match. In such case, there is no need to retransmit the resource since the client still has a previously-downloaded copy.
- 305 Use Proxy (since HTTP/1.1)
- The requested resource is available only through a proxy, the address for which is provided in the response. For security reasons, many HTTP clients (such as Mozilla Firefox and Internet Explorer) do not obey this status code.
- 306 Switch Proxy
- No longer used. Originally meant «Subsequent requests should use the specified proxy.»
- 307 Temporary Redirect (since HTTP/1.1)
- In this case, the request should be repeated with another URI; however, future requests should still use the original URI. In contrast to how 302 was historically implemented, the request method is not allowed to be changed when reissuing the original request. For example, a POST request should be repeated using another POST request.
- 308 Permanent Redirect
- This and all future requests should be directed to the given URI. 308 parallel the behaviour of 301, but does not allow the HTTP method to change. So, for example, submitting a form to a permanently redirected resource may continue smoothly.
4xx client errors
This class of status code is intended for situations in which the error seems to have been caused by the client. Except when responding to a HEAD request, the server should include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes are applicable to any request method. User agents should display any included entity to the user.
- 400 Bad Request
- The server cannot or will not process the request due to an apparent client error (e.g., malformed request syntax, size too large, invalid request message framing, or deceptive request routing).
- 401 Unauthorized
- Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource. See Basic access authentication and Digest access authentication. 401 semantically means «unauthorised», the user does not have valid authentication credentials for the target resource.
- Some sites incorrectly issue HTTP 401 when an IP address is banned from the website (usually the website domain) and that specific address is refused permission to access a website.[citation needed]
- 402 Payment Required
- Reserved for future use. The original intention was that this code might be used as part of some form of digital cash or micropayment scheme, as proposed, for example, by GNU Taler,[14] but that has not yet happened, and this code is not widely used. Google Developers API uses this status if a particular developer has exceeded the daily limit on requests.[15] Sipgate uses this code if an account does not have sufficient funds to start a call.[16] Shopify uses this code when the store has not paid their fees and is temporarily disabled.[17] Stripe uses this code for failed payments where parameters were correct, for example blocked fraudulent payments.[18]
- 403 Forbidden
- The request contained valid data and was understood by the server, but the server is refusing action. This may be due to the user not having the necessary permissions for a resource or needing an account of some sort, or attempting a prohibited action (e.g. creating a duplicate record where only one is allowed). This code is also typically used if the request provided authentication by answering the WWW-Authenticate header field challenge, but the server did not accept that authentication. The request should not be repeated.
- 404 Not Found
- The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.
- 405 Method Not Allowed
- A request method is not supported for the requested resource; for example, a GET request on a form that requires data to be presented via POST, or a PUT request on a read-only resource.
- 406 Not Acceptable
- The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request. See Content negotiation.
- 407 Proxy Authentication Required
- The client must first authenticate itself with the proxy.
- 408 Request Timeout
- The server timed out waiting for the request. According to HTTP specifications: «The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time.»
- 409 Conflict
- Indicates that the request could not be processed because of conflict in the current state of the resource, such as an edit conflict between multiple simultaneous updates.
- 410 Gone
- Indicates that the resource requested was previously in use but is no longer available and will not be available again. This should be used when a resource has been intentionally removed and the resource should be purged. Upon receiving a 410 status code, the client should not request the resource in the future. Clients such as search engines should remove the resource from their indices. Most use cases do not require clients and search engines to purge the resource, and a «404 Not Found» may be used instead.
- 411 Length Required
- The request did not specify the length of its content, which is required by the requested resource.
- 412 Precondition Failed
- The server does not meet one of the preconditions that the requester put on the request header fields.
- 413 Payload Too Large
- The request is larger than the server is willing or able to process. Previously called «Request Entity Too Large» in RFC 2616.[19]
- 414 URI Too Long
- The URI provided was too long for the server to process. Often the result of too much data being encoded as a query-string of a GET request, in which case it should be converted to a POST request. Called «Request-URI Too Long» previously in RFC 2616.[20]
- 415 Unsupported Media Type
- The request entity has a media type which the server or resource does not support. For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format.
- 416 Range Not Satisfiable
- The client has asked for a portion of the file (byte serving), but the server cannot supply that portion. For example, if the client asked for a part of the file that lies beyond the end of the file. Called «Requested Range Not Satisfiable» previously RFC 2616.[21]
- 417 Expectation Failed
- The server cannot meet the requirements of the Expect request-header field.[22]
- 418 I’m a teapot (RFC 2324, RFC 7168)
- This code was defined in 1998 as one of the traditional IETF April Fools’ jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers. The RFC specifies this code should be returned by teapots requested to brew coffee.[23] This HTTP status is used as an Easter egg in some websites, such as Google.com’s «I’m a teapot» easter egg.[24][25][26] Sometimes, this status code is also used as a response to a blocked request, instead of the more appropriate 403 Forbidden.[27][28]
- 421 Misdirected Request
- The request was directed at a server that is not able to produce a response (for example because of connection reuse).
- 422 Unprocessable Entity
- The request was well-formed but was unable to be followed due to semantic errors.[9]
- 423 Locked (WebDAV; RFC 4918)
- The resource that is being accessed is locked.[9]
- 424 Failed Dependency (WebDAV; RFC 4918)
- The request failed because it depended on another request and that request failed (e.g., a PROPPATCH).[9]
- 425 Too Early (RFC 8470)
- Indicates that the server is unwilling to risk processing a request that might be replayed.
- 426 Upgrade Required
- The client should switch to a different protocol such as TLS/1.3, given in the Upgrade header field.
- 428 Precondition Required (RFC 6585)
- The origin server requires the request to be conditional. Intended to prevent the ‘lost update’ problem, where a client GETs a resource’s state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.[29]
- 429 Too Many Requests (RFC 6585)
- The user has sent too many requests in a given amount of time. Intended for use with rate-limiting schemes.[29]
- 431 Request Header Fields Too Large (RFC 6585)
- The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large.[29]
- 451 Unavailable For Legal Reasons (RFC 7725)
- A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource.[30] The code 451 was chosen as a reference to the novel Fahrenheit 451 (see the Acknowledgements in the RFC).
5xx server errors
The server failed to fulfil a request.
Response status codes beginning with the digit «5» indicate cases in which the server is aware that it has encountered an error or is otherwise incapable of performing the request. Except when responding to a HEAD request, the server should include an entity containing an explanation of the error situation, and indicate whether it is a temporary or permanent condition. Likewise, user agents should display any included entity to the user. These response codes are applicable to any request method.
- 500 Internal Server Error
- A generic error message, given when an unexpected condition was encountered and no more specific message is suitable.
- 501 Not Implemented
- The server either does not recognize the request method, or it lacks the ability to fulfil the request. Usually this implies future availability (e.g., a new feature of a web-service API).
- 502 Bad Gateway
- The server was acting as a gateway or proxy and received an invalid response from the upstream server.
- 503 Service Unavailable
- The server cannot handle the request (because it is overloaded or down for maintenance). Generally, this is a temporary state.[31]
- 504 Gateway Timeout
- The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.
- 505 HTTP Version Not Supported
- The server does not support the HTTP version used in the request.
- 506 Variant Also Negotiates (RFC 2295)
- Transparent content negotiation for the request results in a circular reference.[32]
- 507 Insufficient Storage (WebDAV; RFC 4918)
- The server is unable to store the representation needed to complete the request.[9]
- 508 Loop Detected (WebDAV; RFC 5842)
- The server detected an infinite loop while processing the request (sent instead of 208 Already Reported).
- 510 Not Extended (RFC 2774)
- Further extensions to the request are required for the server to fulfil it.[33]
- 511 Network Authentication Required (RFC 6585)
- The client needs to authenticate to gain network access. Intended for use by intercepting proxies used to control access to the network (e.g., «captive portals» used to require agreement to Terms of Service before granting full Internet access via a Wi-Fi hotspot).[29]
Unofficial codes
The following codes are not specified by any standard.
- 218 This is fine (Apache HTTP Server)
- Used by Apache servers. A catch-all error condition allowing the passage of message bodies through the server when the
ProxyErrorOverridesetting is enabled. It is displayed in this situation instead of a 4xx or 5xx error message.[34] - 419 Page Expired (Laravel Framework)
- Used by the Laravel Framework when a CSRF Token is missing or expired.[citation needed]
- 420 Method Failure (Spring Framework)
- A deprecated response used by the Spring Framework when a method has failed.[35]
- 420 Enhance Your Calm (Twitter)
- Returned by version 1 of the Twitter Search and Trends API when the client is being rate limited; versions 1.1 and later use the 429 Too Many Requests response code instead.[36] The phrase «Enhance your calm» comes from the 1993 movie Demolition Man, and its association with this number is likely a reference to cannabis.[citation needed]
- 430 Request Header Fields Too Large (Shopify)
- Used by Shopify, instead of the 429 Too Many Requests response code, when too many URLs are requested within a certain time frame.[37]
- 450 Blocked by Windows Parental Controls (Microsoft)
- The Microsoft extension code indicated when Windows Parental Controls are turned on and are blocking access to the requested webpage.[38]
- 498 Invalid Token (Esri)
- Returned by ArcGIS for Server. Code 498 indicates an expired or otherwise invalid token.[39]
- 499 Token Required (Esri)
- Returned by ArcGIS for Server. Code 499 indicates that a token is required but was not submitted.[39]
- 509 Bandwidth Limit Exceeded (Apache Web Server/cPanel)
- The server has exceeded the bandwidth specified by the server administrator; this is often used by shared hosting providers to limit the bandwidth of customers.[40]
- 529 Site is overloaded
- Used by Qualys in the SSLLabs server testing API to signal that the site can’t process the request.[41]
- 530 Site is frozen
- Used by the Pantheon Systems web platform to indicate a site that has been frozen due to inactivity.[42]
- 598 (Informal convention) Network read timeout error
- Used by some HTTP proxies to signal a network read timeout behind the proxy to a client in front of the proxy.[43]
- 599 Network Connect Timeout Error
- An error used by some HTTP proxies to signal a network connect timeout behind the proxy to a client in front of the proxy.
Internet Information Services
Microsoft’s Internet Information Services (IIS) web server expands the 4xx error space to signal errors with the client’s request.
- 440 Login Time-out
- The client’s session has expired and must log in again.[44]
- 449 Retry With
- The server cannot honour the request because the user has not provided the required information.[45]
- 451 Redirect
- Used in Exchange ActiveSync when either a more efficient server is available or the server cannot access the users’ mailbox.[46] The client is expected to re-run the HTTP AutoDiscover operation to find a more appropriate server.[47]
IIS sometimes uses additional decimal sub-codes for more specific information,[48] however these sub-codes only appear in the response payload and in documentation, not in the place of an actual HTTP status code.
nginx
The nginx web server software expands the 4xx error space to signal issues with the client’s request.[49][50]
- 444 No Response
- Used internally[51] to instruct the server to return no information to the client and close the connection immediately.
- 494 Request header too large
- Client sent too large request or too long header line.
- 495 SSL Certificate Error
- An expansion of the 400 Bad Request response code, used when the client has provided an invalid client certificate.
- 496 SSL Certificate Required
- An expansion of the 400 Bad Request response code, used when a client certificate is required but not provided.
- 497 HTTP Request Sent to HTTPS Port
- An expansion of the 400 Bad Request response code, used when the client has made a HTTP request to a port listening for HTTPS requests.
- 499 Client Closed Request
- Used when the client has closed the request before the server could send a response.
Cloudflare
Cloudflare’s reverse proxy service expands the 5xx series of errors space to signal issues with the origin server.[52]
- 520 Web Server Returned an Unknown Error
- The origin server returned an empty, unknown, or unexpected response to Cloudflare.[53]
- 521 Web Server Is Down
- The origin server refused connections from Cloudflare. Security solutions at the origin may be blocking legitimate connections from certain Cloudflare IP addresses.
- 522 Connection Timed Out
- Cloudflare timed out contacting the origin server.
- 523 Origin Is Unreachable
- Cloudflare could not reach the origin server; for example, if the DNS records for the origin server are incorrect or missing.
- 524 A Timeout Occurred
- Cloudflare was able to complete a TCP connection to the origin server, but did not receive a timely HTTP response.
- 525 SSL Handshake Failed
- Cloudflare could not negotiate a SSL/TLS handshake with the origin server.
- 526 Invalid SSL Certificate
- Cloudflare could not validate the SSL certificate on the origin web server. Also used by Cloud Foundry’s gorouter.
- 527 Railgun Error
- Error 527 indicates an interrupted connection between Cloudflare and the origin server’s Railgun server.[54]
- 530
- Error 530 is returned along with a 1xxx error.[55]
AWS Elastic Load Balancing
Amazon Web Services’ Elastic Load Balancing adds a few custom return codes to signal issues either with the client request or with the origin server.[56]
- 460
- Client closed the connection with the load balancer before the idle timeout period elapsed. Typically when client timeout is sooner than the Elastic Load Balancer’s timeout.[56]
- 463
- The load balancer received an X-Forwarded-For request header with more than 30 IP addresses.[56]
- 464
- Incompatible protocol versions between Client and Origin server.[56]
- 561 Unauthorized
- An error around authentication returned by a server registered with a load balancer. You configured a listener rule to authenticate users, but the identity provider (IdP) returned an error code when authenticating the user.[56]
Caching warning codes (obsoleted)
The following caching related warning codes were specified under RFC 7234. Unlike the other status codes above, these were not sent as the response status in the HTTP protocol, but as part of the «Warning» HTTP header.[57][58]
Since this «Warning» header is often neither sent by servers nor acknowledged by clients, this header and its codes were obsoleted by the HTTP Working Group in 2022 with RFC 9111.[59]
- 110 Response is Stale
- The response provided by a cache is stale (the content’s age exceeds a maximum age set by a Cache-Control header or heuristically chosen lifetime).
- 111 Revalidation Failed
- The cache was unable to validate the response, due to an inability to reach the origin server.
- 112 Disconnected Operation
- The cache is intentionally disconnected from the rest of the network.
- 113 Heuristic Expiration
- The cache heuristically chose a freshness lifetime greater than 24 hours and the response’s age is greater than 24 hours.
- 199 Miscellaneous Warning
- Arbitrary, non-specific warning. The warning text may be logged or presented to the user.
- 214 Transformation Applied
- Added by a proxy if it applies any transformation to the representation, such as changing the content encoding, media type or the like.
- 299 Miscellaneous Persistent Warning
- Same as 199, but indicating a persistent warning.
See also
- Custom error pages
- List of FTP server return codes
- List of HTTP header fields
- List of SMTP server return codes
- Common Log Format
Explanatory notes
- ^ Emphasised words and phrases such as must and should represent interpretation guidelines as given by RFC 2119
References
- ^ a b c «Hypertext Transfer Protocol (HTTP) Status Code Registry». Iana.org. Archived from the original on December 11, 2011. Retrieved January 8, 2015.
- ^ Fielding, Roy T. «RFC 9110: HTTP Semantics and Content, Section 10.1.1 «Expect»«.
- ^ Goland, Yaronn; Whitehead, Jim; Faizi, Asad; Carter, Steve R.; Jensen, Del (February 1999). HTTP Extensions for Distributed Authoring – WEBDAV. IETF. doi:10.17487/RFC2518. RFC 2518. Retrieved October 24, 2009.
- ^ «102 Processing — HTTP MDN». 102 status code is deprecated
- ^ Oku, Kazuho (December 2017). An HTTP Status Code for Indicating Hints. IETF. doi:10.17487/RFC8297. RFC 8297. Retrieved December 20, 2017.
- ^ Stewart, Mark; djna. «Create request with POST, which response codes 200 or 201 and content». Stack Overflow. Archived from the original on October 11, 2016. Retrieved October 16, 2015.
- ^ «RFC 9110: HTTP Semantics and Content, Section 15.3.4».
- ^ «RFC 9110: HTTP Semantics and Content, Section 7.7».
- ^ a b c d e Dusseault, Lisa, ed. (June 2007). HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV). IETF. doi:10.17487/RFC4918. RFC 4918. Retrieved October 24, 2009.
- ^ Delta encoding in HTTP. IETF. January 2002. doi:10.17487/RFC3229. RFC 3229. Retrieved February 25, 2011.
- ^ a b «RFC 9110: HTTP Semantics and Content, Section 15.4 «Redirection 3xx»«.
- ^ Berners-Lee, Tim; Fielding, Roy T.; Nielsen, Henrik Frystyk (May 1996). Hypertext Transfer Protocol – HTTP/1.0. IETF. doi:10.17487/RFC1945. RFC 1945. Retrieved October 24, 2009.
- ^ «The GNU Taler tutorial for PHP Web shop developers 0.4.0». docs.taler.net. Archived from the original on November 8, 2017. Retrieved October 29, 2017.
- ^ «Google API Standard Error Responses». 2016. Archived from the original on May 25, 2017. Retrieved June 21, 2017.
- ^ «Sipgate API Documentation». Archived from the original on July 10, 2018. Retrieved July 10, 2018.
- ^ «Shopify Documentation». Archived from the original on July 25, 2018. Retrieved July 25, 2018.
- ^ «Stripe API Reference – Errors». stripe.com. Retrieved October 28, 2019.
- ^ «RFC2616 on status 413». Tools.ietf.org. Archived from the original on March 7, 2011. Retrieved November 11, 2015.
- ^ «RFC2616 on status 414». Tools.ietf.org. Archived from the original on March 7, 2011. Retrieved November 11, 2015.
- ^ «RFC2616 on status 416». Tools.ietf.org. Archived from the original on March 7, 2011. Retrieved November 11, 2015.
- ^ TheDeadLike. «HTTP/1.1 Status Codes 400 and 417, cannot choose which». serverFault. Archived from the original on October 10, 2015. Retrieved October 16, 2015.
- ^ Larry Masinter (April 1, 1998). Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0). doi:10.17487/RFC2324. RFC 2324.
Any attempt to brew coffee with a teapot should result in the error code «418 I’m a teapot». The resulting entity body MAY be short and stout.
- ^ I’m a teapot
- ^ Barry Schwartz (August 26, 2014). «New Google Easter Egg For SEO Geeks: Server Status 418, I’m A Teapot». Search Engine Land. Archived from the original on November 15, 2015. Retrieved November 4, 2015.
- ^ «Google’s Teapot». Retrieved October 23, 2017.[dead link]
- ^ «Enable extra web security on a website». DreamHost. Retrieved December 18, 2022.
- ^ «I Went to a Russian Website and All I Got Was This Lousy Teapot». PCMag. Retrieved December 18, 2022.
- ^ a b c d Nottingham, M.; Fielding, R. (April 2012). «RFC 6585 – Additional HTTP Status Codes». Request for Comments. Internet Engineering Task Force. Archived from the original on May 4, 2012. Retrieved May 1, 2012.
- ^ Bray, T. (February 2016). «An HTTP Status Code to Report Legal Obstacles». ietf.org. Archived from the original on March 4, 2016. Retrieved March 7, 2015.
- ^ alex. «What is the correct HTTP status code to send when a site is down for maintenance?». Stack Overflow. Archived from the original on October 11, 2016. Retrieved October 16, 2015.
- ^ Holtman, Koen; Mutz, Andrew H. (March 1998). Transparent Content Negotiation in HTTP. IETF. doi:10.17487/RFC2295. RFC 2295. Retrieved October 24, 2009.
- ^ Nielsen, Henrik Frystyk; Leach, Paul; Lawrence, Scott (February 2000). An HTTP Extension Framework. IETF. doi:10.17487/RFC2774. RFC 2774. Retrieved October 24, 2009.
- ^ «218 This is fine — HTTP status code explained». HTTP.dev. Retrieved July 25, 2023.
{{cite web}}: CS1 maint: url-status (link) - ^ «Enum HttpStatus». Spring Framework. org.springframework.http. Archived from the original on October 25, 2015. Retrieved October 16, 2015.
- ^ «Twitter Error Codes & Responses». Twitter. 2014. Archived from the original on September 27, 2017. Retrieved January 20, 2014.
- ^ «HTTP Status Codes and SEO: what you need to know». ContentKing. Retrieved August 9, 2019.
- ^ «Screenshot of error page». Archived from the original (bmp) on May 11, 2013. Retrieved October 11, 2009.
- ^ a b «Using token-based authentication». ArcGIS Server SOAP SDK. Archived from the original on September 26, 2014. Retrieved September 8, 2014.
- ^ «HTTP Error Codes and Quick Fixes». Docs.cpanel.net. Archived from the original on November 23, 2015. Retrieved October 15, 2015.
- ^ «SSL Labs API v3 Documentation». github.com.
- ^ «Platform Considerations | Pantheon Docs». pantheon.io. Archived from the original on January 6, 2017. Retrieved January 5, 2017.
- ^ «HTTP status codes — ascii-code.com». www.ascii-code.com. Archived from the original on January 7, 2017. Retrieved December 23, 2016.
- ^
«Error message when you try to log on to Exchange 2007 by using Outlook Web Access: «440 Login Time-out»«. Microsoft. 2010. Retrieved November 13, 2013. - ^ «2.2.6 449 Retry With Status Code». Microsoft. 2009. Archived from the original on October 5, 2009. Retrieved October 26, 2009.
- ^ «MS-ASCMD, Section 3.1.5.2.2». Msdn.microsoft.com. Archived from the original on March 26, 2015. Retrieved January 8, 2015.
- ^ «Ms-oxdisco». Msdn.microsoft.com. Archived from the original on July 31, 2014. Retrieved January 8, 2015.
- ^ «The HTTP status codes in IIS 7.0». Microsoft. July 14, 2009. Archived from the original on April 9, 2009. Retrieved April 1, 2009.
- ^ «ngx_http_request.h». nginx 1.9.5 source code. nginx inc. Archived from the original on September 19, 2017. Retrieved January 9, 2016.
- ^ «ngx_http_special_response.c». nginx 1.9.5 source code. nginx inc. Archived from the original on May 8, 2018. Retrieved January 9, 2016.
- ^ «return» directive Archived March 1, 2018, at the Wayback Machine (http_rewrite module) documentation.
- ^ «Troubleshooting: Error Pages». Cloudflare. Archived from the original on March 4, 2016. Retrieved January 9, 2016.
- ^ «Error 520: web server returns an unknown error». Cloudflare.
- ^ «527 Error: Railgun Listener to origin error». Cloudflare. Archived from the original on October 13, 2016. Retrieved October 12, 2016.
- ^ «Error 530». Cloudflare. Retrieved November 1, 2019.
- ^ a b c d e «Troubleshoot Your Application Load Balancers – Elastic Load Balancing». docs.aws.amazon.com. Retrieved May 17, 2023.
- ^ «Hypertext Transfer Protocol (HTTP/1.1): Caching». datatracker.ietf.org. Retrieved September 25, 2021.
- ^ «Warning — HTTP | MDN». developer.mozilla.org. Retrieved August 15, 2021.
Some text was copied from this source, which is available under a Creative Commons Attribution-ShareAlike 2.5 Generic (CC BY-SA 2.5) license.
- ^ «RFC 9111: HTTP Caching, Section 5.5 «Warning»«. June 2022.
External links
- «RFC 9110: HTTP Semantics and Content, Section 15 «Status Codes»«.
- Hypertext Transfer Protocol (HTTP) Status Code Registry at the Internet Assigned Numbers Authority
- HTTP status codes at http-statuscode.com
- MDN status code reference at mozilla.org
Умные люди придумали коды, по которым можно определить, что произошло с HTTP-запросом. Успешен ли он, произошло ли перенаправление. Или же все закончилось ошибкой. Как раз об ошибках и будем говорить в этой статье. Вкратце расскажу, какие они бывают и с чем связаны.
А еще тут будет парочка забавных (и не очень) пикч и анимаций на тему описанных ошибок. Хоть какое-то развлечение.
Ошибки со стороны клиента (4xx)
Для начала перечислим коды ошибок на стороне клиента. Вина за их появление ложится на плечи обоих участников соединения.
400 Bad Request
Такой ответ от браузера можно получить в том случае, если сервер не смог правильно отреагировать на запрос со стороны пользователя. Часто код 400 возникает при попытке клиента получить доступ к серверу без соблюдения правил оформления синтаксиса протокола передачи гипертекста (HTTP). Повторный запрос не стоит отправлять до тех пор, пока не будет исправлена ошибка (или несколько из них).
401 Unauthorized
Код 401 возникает при попытке клиента получить доступ к серверу, используя неправильные данные для авторизации. По сути, используется, когда пользователь вводит неправильный логин и пароль на ресурсе, где требуется эта информация для входа. Читайте: Как исправить ошибку 401
402 Payment Required
Эта ошибка сообщает клиенту о том, что для успешного выполнения запроса ему необходимо оплатить доступ к серверу. Изначально код 402 должен был стать неким стандартом для цифровой валюты и оплаты контента в сети. Но не срослось. До сих пор нет единого решения по поводу того, как должны выглядеть платежи в сети. Также нет и единого решения по поводу того, как стоит использовать 402.
Все еще считается, что код существует с расчетом на будущее. Сейчас почти не используется и поддерживается не всеми браузерами.
403 Forbidden
Почти то же, что и 401. Сервер снова не разрешает к нему подключиться, хотя с запросом все в порядке. Просто нет доступа. Причем повторная авторизация с другими логином и паролем никак не помогут. Все вопросы к владельцам сервера (но не всегда). Инструкция по устранению ошибки.
Творчество на тему знаменитой киносаги
404 Not Found
Легендарная ошибка, ставшая популярным мемом. 404 оповещает клиента о том, что его запрос ведет в никуда. Код возникает, когда пользователь пытается попасть на страницу, которой не существует. Например, когда случайно ошибается при вводе ссылки и вводит ее с опечаткой. Или же пытается получить доступ к странице, которой на сайте уже нет.
В отличие от других кодов, страницу с 404 частенько кастомизируют, создавая для нее уникальный дизайн. Мало того, что это выглядит симпатичнее, так еще и полезнее для посетителей. Можно прямо на странице с ошибкой разъяснить, что произошло и как дальше действовать.
И таких вариаций тысячи. Каждый пытается добавить в оформление что-то свое.
405 Method Not Allowed
405 сообщает клиенту о том, что метод, используемый при запросе, не разрешен. В качестве примера можно привести попытку со стороны клиента ввести данные в форму с помощью GET, когда она работает только с POST. Ну и в таком же духе.
406 Not Acceptable
Ошибка 406 сообщает о том, что страница передает контент, который не может быть распознан клиентом. Возможно, проблема в методе сжатия или в формате страницы. Иногда сюда же приплетают неправильные настройки кодировки.
Этот код редко используют на практике, так как его появления можно избежать, предоставив пользователю информацию на сайте в том виде, который его браузер способен принять. Посетитель сайта по итогу получит не то, что ожидал, но хотя бы не ошибку.
407 Proxy Authentication Required
Этот код тоже похож на 401. Только на этот раз логин и пароль нужны не для основного сервера, а для прокси, который находится между клиентом и сервером. Обычно в теле ошибки содержится информация о том, как можно правильно пройти авторизацию и получить доступ к ресурсу.
408 Request Timeout
408 говорит нам о том, что сервер пожелал разорвать соединение с клиентом, потому что оно никак не используется. Происходит это в том случае, если сервер буквально устал ждать, пока наладится соединение с ним. Поэтому такую ошибку часто можно лицезреть после очень долгой и безуспешной загрузки какого-нибудь сайта.
Многие серверы не отправляют никаких сообщений, а просто прерывают соединение по той же причине. На запрос уходит больше времени, чем на то полагается.
В Мистере Роботе частенько называли серии в честь ошибок HTTP (весь четвертый сезон в нумерации 4хх). В честь 408, например, назвали восьмую серию четвертого сезона
409 Conflict
Сообщение о конфликте возникает, когда запрос со стороны клиента не соответствует тому, чего ожидает сервер. В качестве примера приводят проблемы при проверки версий, когда пользователь пытается с помощью метода PUT загрузить на сервер новый файл, но там уже имеется более новая версия того же файла. Конфликта версий можно легко избежать, загрузив корректную версию.
410 Gone
Своего рода аналог 404. Разница лишь в том, что 410 намекает на перманентность отсутствия страницы. Так что этот код стоит использовать, когда на 100% уверен, что страница ушла в небытие (ну или с текущего адреса) навсегда. В любом другом случае есть универсальный 404.
411 Length Required
411 оповещает пользователя о том, что сервер не желает принимать запрос со стороны клиента, потому что в нем не определен заголовок Content-Length. Да, это первый код в подборке, который смогут понять только люди, сведущие в настройке серверов. По-простому уложить сущность HTML-заголовков в этот материал не получится.
412 Precondition Failed
Еще один код, сообщающий о том, что сервер отклонил запрос пользователя и не разрешает доступ к выбранному ресурсу. Проблемы возникают при неправильной настройке работы методов, отличающихся от GET и HEAD.
413 Payload Too Large/Request Entity Too Large
Код 413 говорит нам, что запрос, который посылает клиент на сервер, слишком большой. Поэтому сервер отказывается его обрабатывать и разрывает соединение. Обычно это происходит при попытке загрузить на ресурс какой-то файл, превышающий ограничение, выставленное в настройках сервера. Соответственно, решается проблема изменением настроек сервера.
414 URI Too Long
Чем-то этот код похож на предыдущий. Здесь тоже идет речь о превышение лимита. Только теперь это касается не запроса со стороны клиента, а длины URI. То есть ссылки. Выходит, что адрес, используемый клиентом, больше, чем тот, что может обработать сервер. Как-то так.
Такая ошибка иногда выскакивает при попытке взломать ресурс. Сайт так реагирует на слишком частые попытки воспользоваться потенциальными дырами в безопасности.
415 Unsupported Media Type
Ошибка 415 возникает, когда клиент пытается загрузить на сервер данные в неподходящем формате. В таком случае сервер просто отказывается принимать посылаемые файлы и разрывает соединение. Как и в случае с 413.
416 Range Not Satisfiable
Подобный ответ можно ожидать, если клиент запрашивает у сервера определенные данные, но эти данные на сервере не соответствуют запросу. То есть, грубо говоря, вы просите у сервера какой-то набор данных с заранее заданным размером, а в итоге оказывается, что размер этих данных меньше, чем объем, указанный в запросе. Серверу ничего не остается, кроме как послать вас, ведь он не обучен поведению в таких ситуациях.
417 Expectation Failed
Такая ошибка высвечивается, когда ожидания сервера не совпадают с данными в запросе клиента. Сведения об ожиданиях прописываются в заголовке Expect заранее. Так что можно ознакомиться с ними, чтобы выяснить, как решить названную проблему.
418 I’m a teapot
Код 418 можно увидеть, если сервер откажется варить кофе, потому что он чайник. Это первоапрельская шутка. Естественно, 418 не используется нигде всерьез и просто существует как дань памяти программистам-юмористам, придумавшим это в 1998 году.
У Google получился такой симпатичный чайник
421 Misdirected Request
Появляется когда запрос клиента переправляется на сервер, который не может дать на него адекватный ответ. Например, если запрос был отправлен на ресурс, который вообще не настроен обрабатывать запросы извне.
Чтобы исправить проблему, можно попробовать переподключиться к ресурсу заново или попробовать другое соединение.
422 Unprocessable Entity
Код 422 говорит, что сервер вроде бы принял запрос, понял его, все хорошо, но из-за семантических ошибок корректно обработать не смог. Значит, где-то в запросе затаилась логическая ошибка, мешающая корректному взаимодействию клиента и сервера. Надо ее найти и исправить.
423 Locked
Обычно на этот код напарываются, когда запрашиваемый ресурс оказывается под защитой. Используемые клиентом методы блокируются на уровне сервера. Это делается, чтобы обезопасить данные, хранящиеся на защищенной странице. Без логина и пароля выудить информацию с такого сервера не получится.
424 Failed Dependency
424 сообщает о том, что для выполнения запроса со стороны клиента успешно должна завершиться еще одна или несколько параллельных операций. Если какая-то из них «провалится», то «помрет» все соединение сразу, и обработать запрос до конца не получится. Аналогичное происходит, если некорректно был обработан один из предыдущих запросов.
425 Too Early
Появляется в ответ на запрос, который может быть моментально запущен заново. Сервер не рискует и не берется за его обработку, чтобы не подставиться под так называемую «атаку повторного воспроизведения».
426 Upgrade Required
Тут нам прямо сообщают, что сервер не желает с нами общаться, пока мы не перейдем на более современный протокол. Наткнуться на такую ошибку очень тяжело, но в случае появления, скорее всего, будет достаточно установить браузер посвежее.
428 Precondition Required
428 выскакивает, если пользователь отправляет запрос на сервер, но получает некорректные или неактуальные данные. Так ресурс оповещает о необходимости внести в запрос информацию о предварительных условиях обработки данных. Только так он сможет гарантировать получение клиентом нужной информации.
429 Too Many Requests
Здесь все просто. Ошибка появляется, когда клиент отправляет на сервер слишком много запросов в короткий промежуток времени. Очень похоже на поведение взломщиков. По этой причине запрос моментально блокируется.
431 Request Header Fields Too Large
Из названия понятно, что ошибка с кодом 431 появляется из-за того, что в запросе клиента используются слишком длинные заголовки (неважно, один или несколько из них). Исправляется это с помощью сокращения заголовков и повторной отправки запроса. В теле ошибки обычно отображается краткая информация о том, как пользователь может решить эту проблему самостоятельно.
444 No Response
Этот код вам вряд ли удастся увидеть. Он отображается в лог-файлах, чтобы подтвердить, что сервер никак не отреагировал на запрос пользователя и прервал соединение.
449 Retry With
Код используется в расширениях компании Microsoft. Он сигнализирует о том, что запрос от клиента не может быть принят сервером. Причиной становятся неверно указанные параметры. Сама 449 ошибка говорит о необходимости скорректировать запрос и повторить его снова, подготовив к работе с сервером.
450 Blocked by Windows Parental Controls
450 код увидят дети, попавшие под действие системы «Родительский контроль» компании Microsoft. По сути, ошибка говорит о том, что с компьютера попытались зайти на заблокированный ресурс. Избежать этой ошибки можно изменением параметров родительского контроля.
451 Unavailable For Legal Reasons
Этот код сообщает клиенту, что он не может попасть на запрашиваемый ресурс из юридических соображений. Скорее всего, доступ был заблокирован из-за каких-нибудь государственных санкций, нового законодательства или цензуры со стороны властей. В общем, все вопросы к государству и провайдеру связи.
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Список ошибок на стороне сервера (5xx)
Теперь поговорим об ошибках, которые возникают где-то на сервере. Все они связаны с запросами, которые не удается обработать на том конце. Пользователь зачастую в их появлении не виноват.
500 Internal Server Error
Этот код возникает, когда сервер сталкивается с непредвиденными обстоятельствами. Такими, которые и сам не может пояснить. Как, собственно, и завершить запрос со стороны пользователя. По факту, эта ошибка говорит нам что-то вроде «Я не могу подобрать более подходящий код ошибки, поэтому лови 500 и делай с этим, что хочешь». Мы писали о нем чуть подробнее тут.
Дело не в тебе, дело во мне (С)
501 Not Implemented
501 говорит нам, что функциональность, необходимая для обработки запроса со стороны клиента, попросту не реализована на сервере. Он не сможет корректно обработать используемый метод.
Иногда в теле ошибки еще пишут что-то в духе «Приходите попозже, возможно, в будущем нужная функция появится».
502 Bad Getaway
Можно встретить в том случае, если запрашиваемый сервер выступает в роли шлюза или прокси. Возникает из-за несогласования протоколов между вышестоящим серверов и его шлюзом. Рассказываем о том, как ее исправить, в этой статье.
503 Service Unavailable
Появляется, когда сервер не может обработать запрос клиента по одной из двух технических причин:
- Слишком много пользователей в текущий момент пытаются отправить запросы, и у сервера не остается ресурсов, чтобы ответить кому-либо еще.
- На сервере ведутся технические работы, временно блокирующие его работу.
Обычно ошибка 503 носит временный характер, и для ее решения достаточно немного подождать.
504 Gateway Timeout
Ошибка похожа на 408. Здесь же прокси-сервер пытается выйти на контакт с вышестоящим сервером, но не успевает это сделать до истечения тайм-аута. Отсюда и ошибка.
505 HTTP Version Not Supported
Этот код похож на 426. Он тоже связан с неподходящей версией протокола HTTP. В этом случае нужно обеспечить и клиента, и сервер единой версией. Она, как правило, указывается в запросе со стороны пользователя.
506 Variant Also Negotiates
Обычно с такой ошибкой сталкиваются только в том случае, если сервер изначально настроен неправильно. То есть это не сиюминутная проблема, а что-то серьезное на уровне базовой конфигурации. Тут придется потрудиться разработчикам. Выявить проблему и разрешить ее.
507 Insufficient Storage
Код 507 встречается в тех ситуациях, когда серверу не хватает пространства в хранилище для обработки запроса со стороны клиента. Проблема решается освобождением места или расширением доступного пространства. Тогда сервер сможет без проблем обработать запрос пользователя.
508 Loop Detected
Таким кодом сервер отзовется в случае, если заметит бесконечный цикл в запросе клиента. Можно расценивать его как провал запроса и выполняемой операции в целом.
509 Bandwidth Limit Exceeded
Возникает, если сервер начинает потреблять больше трафика, чем ему позволено.
510 Not Extended
Появляется, если клиент посылает запрос на использование какого-либо расширения, отсутствующего на сервере. Чтобы исправить проблему, надо убрать декларирование неподдерживаемого расширения из запроса или добавить поддержку на сервер.
511 Network Authentication Required
511 код говорит о том, что перед тем как выйти в сеть, надо авторизоваться (ввести логин и пароль). Можно воспринимать это неким PPPoE подключением, когда от клиента требуются данные для авторизации.
Заключение
Закончили. Это все ошибки, которыми отзывается HTTP, если на стороне сервера или клиента что-то пошло не так. Наткнуться на большую их часть довольно тяжело. Особенно, если вы раньше только серфили в интернете, а не занимались разработкой сайтов. А тем, кто входит в эту стезю, полезно знать основные ошибки, так как, скорее всего, придется не раз их исправлять.