Did you just try to visit a website only to be met by a message that says Error 451: Unavailable Due to Legal Reasons?
In a nutshell, this error message indicates that the website owner or your local government/authority has blocked access to the website in order to comply with the law in the country from which you’re browsing, even though the website itself might still be working for other visitors.
However, if you really need to access the site, there are some ways that you can “fix” (or bypass) this error message to still view the website in question.
In this article, we’re going to cover everything that you need to know about the Error 451: Unavailable Due to Legal Reasons message.
Check Out Our Video Guide to Fixing The 451 Error
What Is Error 451: Unavailable Due to Legal Reasons?
The Error 451: Unavailable Due to Legal Reasons message is an HTTP error code that displays when the website you’re trying to access has been blocked by the government/authority of the country from which you’re browsing OR when the website owner has blocked you in order to comply with laws.
The error code – 451 – is a reference to Ray Bradbury’s sci-fi novel, Fahrenheit 451. Because of this, you’ll also see Error 451 sometimes called the “censorship error.”
In the error message, you should see details about the name of the organization requesting the block, along with the reasons for the block.
Here’s a humorous example from Mozilla that’s based on Monty Python’s Life of Brian:
HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://spqr.example.org/legislatione>; rel="blocked-by"
Content-Type: text/html
<html>
<head><title>Unavailable For Legal Reasons</title></head>
<body>
<h1>Unavailable For Legal Reasons</h1>
<p>This request may not be serviced in the Roman Province
of Judea due to the Lex Julia Majestatis, which disallows
access to resources hosted on servers deemed to be
operated by the People's Front of Judea.</p>
</body>
</html>
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What Causes Error 451: Unavailable Due to Legal Reasons?
Unlike pretty much all other HTTP errors, the Error 451: Unavailable Due to Legal Reasons message usually has nothing to do with either the website server (hosting) or the client (usually your web browser).
Instead, the error usually means that your internet service provider (ISP) has blocked the site at a network level.
The website could be functioning perfectly normally and your browser could be functioning perfectly normally, but you’ll still get this error because the ISP that you’re using for internet service has blocked the website.
In some cases, the website that you’re trying to visit might display the error by itself in order to comply with a legal order or avoid legal issues, even without the ISP’s involvement. For example, a small number of sites block European traffic and display this error message because the sites don’t want to comply with the GDPR. You can see an example of this in the screenshot from the previous section.
Either way, the important detail to understand is that the error is not caused by any widespread issue on the website or your computer – it’s specifically because of compliance with a law or legal order.
How To Fix Error 451: Unavailable Due to Legal Reasons
Because the Error 451: Unavailable Due to Legal Reasons message indicates that a website is blocked for legal reasons, there’s not necessarily any way to “fix” it in most cases (short of hiring a lawyer and going to court).
However, if you’re trying to access someone else’s website, there are several ways that you can effectively bypass the Error 451: Unavailable Due to Legal Reasons message.
1. Use a VPN (Virtual Private Network)
Using a virtual private network (VPN) can let you bypass the error 451 message by encrypting your connection and routing it through a server in a different country.
Because it looks like you’re browsing from a different country and your ISP is no longer able to see what sites you’re looking at, you should be able to access the site.
Just make sure that you choose a VPN server in a country that isn’t blocked. For example, if you live in France and you’re trying to access a website that blocks European traffic because of the GDPR, choosing a VPN server in Germany won’t solve the problem because German visitors are also blocked. However, choosing a VPN server in the USA would.
To learn more, you can read our full guide on how a VPN works.
If you’re on a tight budget, you can use a free VPN such as ProtonVPN. Or, for more connection options and features, you can consider a paid VPN service such as NordVPN, ExpressVPN, or others.
2. Change Your DNS Resolvers to Cloudflare
Whenever your computer/web browser tries to connect to a website, it needs to use DNS resolvers to look up the IP address of the actual server behind the site’s domain name.
In some situations, you might be seeing the Error 451 because your ISP is blocking the website via the default DNS resolvers that your computer uses.
To try to bypass this, you can use a different DNS resolver. We recommend Cloudflare 1.1.1.1 as the best option, as it’s 100% free and privacy-friendly.
Google also offers its own public DNS resolver, which can be another option to consider.
Cloudflare maintains detailed instructions for how to change the DNS resolver for all popular operating systems and devices. You can find them by going here and scrolling down to the “Setup on…X” section:
3. Enable HTTPS
In some cases, switching to the HTTPS version of a site instead of the HTTP version might help you to bypass the Error 451 message.
Without HTTPS, the data that passes between your web browser and the website is available to anyone sitting in the middle, including your ISP.
With HTTPS, that data is encrypted in transit, which means that your ISP and others can’t snoop on the actual data (though your ISP can still see the site that you’re connecting to, which is why this fix isn’t enough most of the time and a VPN offers more protection).
To see if this will work for your situation, try changing the http part of the domain name to https. If that works, you can use an extension like HTTPS Everywhere to try and automatically force HTTPS usage whenever possible.
4. Use a Proxy Server
Using a proxy server provides another way to route your browser connection through a different server, which can help you bypass the error 451 block.
It works similarly to a VPN, but there are some important differences between a proxy server vs a VPN.
In general, we recommend using a VPN instead of a proxy server whenever possible because quality VPN services are more secure and privacy-friendly. If you’re using a VPN, you do not need a proxy server because the VPN already accomplishes the same thing.
However, if you’re unable to use a VPN for some reason, a proxy server provides another alternative that usually won’t cost any money.
5. Use Tor Browser
For a virtually foolproof way to get around government blocks, you can use Tor via the Tor Browser.
Tor was built by the United States Naval Research Laboratory specifically to protect communication online.
It works by bouncing your connection through a random path of relay servers in the Tor network. Because everything is encrypted and there’s no way to see where the connection originated from, Tor will help you get around the error 451 message (as well as most other types of online censorship).
This is why we recommend Tor Browser as one of the most secure web browsers.
Seeing this error message but still need to access the site? Read on… 👀Click to Tweet
Summary
The Error 451: Unavailable Due to Legal Reasons message indicates that the website you’re trying to visit has been blocked by the government or other “legal obstacles”.
The website could be functioning normally. However, if the authority in your country has issued a legal order, your internet service provider (ISP) can block your access to the site by displaying the Error 451: Unavailable Due to Legal Reasons message.
In some cases, the website owner might display the error code itself to comply with local laws, rather than relying on the ISP. Again, one example is a small number of sites proactively blocking European traffic to avoid complications with GDPR compliance.
To bypass the Error 451 message, you can use tactics that hide your browsing location, such as a VPN, proxy, or Tor Browser. In some cases, changing your DNS provider to Cloudflare or accessing the HTTPS version of the site might also work.
From Wikipedia, the free encyclopedia
In computer networking, HTTP 451 Unavailable For Legal Reasons is a proposed standard error status code of the HTTP protocol to be displayed when the user requests a resource which cannot be served for legal reasons, such as a web page censored by a government. The number 451 is a reference to Ray Bradbury’s 1953 dystopian novel Fahrenheit 451, in which books are outlawed.[2] 451 provides more information than HTTP 403, which is often used for the same purpose.[3] This status code is currently a proposed standard in RFC 7725 but is not yet formally a part of HTTP, as of RFC 9110.
Examples of situations where an HTTP 451 error code could be displayed include web pages deemed a danger to national security, or web pages deemed to violate copyright, privacy, blasphemy laws, or any other law or court order.
After introduction of the GDPR in the EEA it became common practice for websites located outside the EEA to serve HTTP 451 errors to EEA visitors instead of trying to comply with this new privacy law. For instance, many regional U.S. news sites no longer serve web browsers from the EU.[4][5][6]
The RFC is specific that a 451 response does not indicate whether the resource exists but requests for it have been blocked, if the resource has been removed for legal reasons and no longer exists, or even if the resource has never existed, but any discussion of its topic has been legally forbidden (see injunction).[7] Some sites have previously returned HTTP 404 (missing) or similar if they are not legally permitted to disclose that the resource has been removed. It is used in the United Kingdom by some Internet service providers utilising the Internet Watch Foundation blacklist, returning a 404 message or another error message instead of showing a message indicating the site is blocked.[8][9]
The status code was formally proposed in 2013 by Tim Bray, following earlier informal proposals by Chris Applegate[10] in 2008 and Terence Eden[11] in 2012. It was approved by the IETF on December 18, 2015.[12] It was published as in the Proposed Standard RFC 7725 in February 2016.
HTTP 451 was mentioned by the BBC’s From Our Own Correspondent programme, as an indication of the effects of sanctions on Sudan and the inability to access Airbnb, the App Store, or other Western web services.[13]
Usage[edit]
When an entity intercepts the request and returns status 451, it should include a «Link» HTTP header field whose value is a URI reference identifying itself. The «Link» header field must then have a «rel» parameter whose value is «blocked-by». This is intended to identify the entity implementing the blocking (an ISP, DNS provider, caching system, etc.), not the legal authority mandating the block.[14] At an IETF hackathon, participants used a web crawler to discover that several implementations misunderstood this header and gave the legal authority instead.[15]
Additional uses[edit]
The meaning of «a resource which cannot be served for legal reasons» has been interpreted to extend beyond government censorship:
- When content cannot be shown in the user’s country, due to contractual or licensing restrictions with the content owner, for example, a TV program may not be available to users in some countries.
- When a publisher refuses to serve content to a user, because the user’s country adds regulatory requirements that the publisher refuses to comply with, e.g. websites based outside of the EU may refuse to serve users in the EU because they do not want to comply with the GDPR.
Example[edit]
HTTP/1.1 451 Unavailable For Legal Reasons Link: <https://search.example.net/legal>; rel="blocked-by" Content-Type: text/html <html> <head><title>Unavailable For Legal Reasons</title></head> <body> <h1>Unavailable For Legal Reasons</h1> <p>This request may not be serviced in the Roman Province of Judea due to the Lex Julia Majestatis, which disallows access to resources hosted on servers deemed to be operated by the People's Front of Judea.</p> </body> </html>
See also[edit]
- Evil bit
- Gag order
- Superinjunction
- Technological fix
References[edit]
- ^ «Attorney General Shapiro, Governor Wolf, State Police Successfully Block Access to 3D Downloadable Guns in Pennsylvania» (Press release). Pennsylvania Office of Attorney General. 29 July 2018.
- ^ Flood, Alison (22 June 2012). «Call for Ray Bradbury to be honoured with internet error message». The Guardian. Retrieved 22 June 2012.
- ^ Ducklin, Paul (19 August 2013). «HTTP error code 451: «Unavailable For Legal Reasons»«. Naked Security. Sophos.
- ^ Matt Burgess (29 August 2018). «The tyranny of GDPR popups and the websites failing to adapt». WIRED. Retrieved 1 October 2018.
- ^ «More than 1,000 U.S. News sites are still unavailable in Europe, two months after GDPR took effect». www.niemanlab.org.
- ^ «Major US news sites are still blocking Europeans due to GDPR». Engadget. Retrieved 27 July 2023.
- ^ Bray, Tim (February 2016). «451 Unavailable For Legal Reasons». An HTTP Status Code to Report Legal Obstacles. sec. 3. doi:10.17487/RFC7725. RFC 7725.
- ^ «Cleanfeed». ORG Wiki. Open Rights Group.
If the request is for the blocked content then the proxy server will return a 404 error page to the customer
- ^ Arthur, Charles (8 December 2008). «How the IWF blacklist stops you seeing the Scorpions’ album cover». Technology blog, The Guardian.
TCP Reset is sent back to the customer instead of content.
- ^ Applegate, Chris (9 December 2008). «There is no HTTP code for censorship». qwghlm.co.uk. Retrieved 23 December 2015.
- ^ Byrne, Michael (21 December 2015). «The HTTP 451 Error Code for Censorship Is Now an Internet Standard». Vice. Retrieved 3 July 2020.
- ^ Nottingham, Mark (18 December 2015). «Why 451?». mnot’s blog. Retrieved 20 December 2015.
- ^ Sally Hayden (28 September 2017). From Our Own Correspondent (radio). BBC Radio 4.
- ^ Bray, Tim (February 2016). «Identifying Blocking Entities». An HTTP Status Code to Report Legal Obstacles. sec. 4. doi:10.17487/RFC7725. RFC 7725.
- ^ Stéphane Bortzmeyer (11 November 2017). «RFC Errata Report». IETF Tools. Retrieved 3 December 2018.
External links[edit]
Media related to HTTP 451 at Wikimedia Commons
- RFC 7725 – An HTTP Status Code to Report Legal Obstacles
Officially, HTTP response status code 451 Unavailable For Legal Reasons is returned by the server to indicate that the content requested is unavailable due to a legal or legislated demand.
The response is cacheable by default. If the default behavior needs to be overridden then the response must include the appropriate HTTP caching headers.
In addition the HTTP status code 451 Redirect is also used by Microsoft Exchange ActiveSync when the client is attempting to connect to the wrong server, or if there is a more efficient server available to reach the user’s mailbox.
Table of Contents
- Usage
- Microsoft Exchange ActiveSync Usage
- Example
- Code references
- Takeaway
- See also
Usage
When the 451 Unavailable For Legal Reasons status code is received, the server is not confirming nor denying the existence of the resource. Rather, it indicates a refusal to grant access due to a legal demand, and it is permitted to state as much.
Essentially, the resource is being blocked due to censorship, and the HTTP status code pays homage to the Ray Bradbury novel about this topic, Fahrenheit 451.
Examples of where the 451 Unavailable For Legal Reasons response status applies will depend on the laws of the country from which it is being accessed. Some examples include copyright infringement, privacy violations, and gambling sites. Any situation where there is a court order, such as a publication ban, can use this HTTP status code. The 403 Forbidden response status is the more general version of the error.
The transparency afforded by this HTTP status code allows for the easier third-party collection of statistics related to the number, and perhaps a category of sites that are taken down due to censorship.
In some cases, clients can still access the resources by using alternative methods. For example, a VPN or the Tor network can be used to shroud one’s point of origin, or a proxy server can be used to redirect browser traffic to another country.
As part of the response, the server has to include a Link header that identifies the party that blocked the request. Importantly, this is the group responsible for blocking the content, and not the group who mandated it. Information about who set the policy can be included in the message body.
Note
Search engines like Google will not index a URL with 451 Unavailable For Legal Reasons response status, and consequently, URLs that have been indexed in the past but are now returning this HTTP status code will be removed from the search results.
Microsoft Exchange ActiveSync Usage
When the 451 Redirect error message is received, it means that the client is attempting to connect to the wrong server. This is either because the user’s mailbox cannot be accessed from this server or alternatively, there is a more efficient server than can be used.
If there is an X-MS-Location header included in the response then subsequent requests are required to use that address instead. If the X-MS-Location header is not included then the full Autodiscover process is followed.
Example
In the example, the client requests a resource and the server responds with the 451 Unavailable For Legal Reasons.
Request
GET /tech-trial-updates HTTP/1.1
Host: www.example.re
Response
HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://www.example.re/legaldept>; rel=”blocked-by”
Content-Type: text/html
Content-Length: 174
<html>
<head>
<title>Publication Ban</title>
</head>
<body>
<p>The content that you have requested is unavailable due to a government-ordered publication ban.</p>
</body>
</html>
Code references
.NET
HttpStatusCode.UnavailableForLegalReasons
Rust
http::StatusCode::UNAVAILABLE_FOR_LEGAL_REASONS
Rails
:unavailable_for_legal_reasons
Go
http.StatusUnavailableForLegalReasons
Symfony
Response::HTTP_UNAVAILABLE_FOR_LEGAL_REASONS
Python3.5+
http.HTTPStatus.UNAVAILABLE_FOR_LEGAL_REASONS
Apache HttpComponents Core
org.apache.hc.core5.http.HttpStatus.SC_UNAVAILABLE_FOR_LEGAL_REASONS
Angular
@angular/common/http/HttpStatusCode.UnavailableForLegalReasons
Takeaway
The 451 Unavailable For Legal Reasons status code is a client error that is sent by the server when the client requests a document for which access is not allowed by them or from within their geo location and/or locale.
In the case of 451 Redirect issued by Microsoft Exchange ActiveSync, it implies that the client is attempting to connect to the wrong server to access their mailbox.
See also
- 403 Forbidden
- RFC 7725
- Microsoft Exchange ActiveSync HTTP 451 Error
Last updated: August 2, 2023
What is a 451 Unavailable For Legal Reasons HTTP response?
Usage of the 451 HTTP status response code is suitable for situations where a resource must be blocked for legal reasons, such as where a court judgement or law requires that content should be made unavailable.
451 has been used widely by US news/media sites following the introduction of EU ‘GDPR’ privacy regulations, blocking content for EU visitors.
The 451 HTTP status was actually only introduced quite recently in 2016 – in order to provide more information than previous alternatives such as 403 forbidden.
What type of HTTP status is a 451?
A 451 is in the 4xx class of status codes which are client error based.
Example 451 response
451 Unavailable For Legal Reasons
Example of a 451 HTTP response shown to EU website users
Example 451 response in the Chrome network tab
When should a 451 response be used?
A 451 response is suitable for any situation whereby a court or other legal entity has mandated that a web resource must be removed or blocked.
Examples might include: criminal court cases, civil court cases, tribunals, statutes/laws, treaties, or simply a request from a company legal department.
A 451 response does not necessarily have to be served globally. For example many US news sites show a 451 status and message to European users to get around GDPR privacy requirements.
Does a 451 HTTP status affect SEO?
If you want to block all users for legal reasons – then a 451 code is perfect – and will also likely remove your site from search engines.
If Google are unable to access a resource it is likely that they will not index it. If all users/bots that attempt to access a resource are served with a 451 response and no content, it will not be indexed.
However from testing conducted at the time of writing: if US users and Googlebot are able to access the content then this content will be indexable/potentially available in Google search.
Specification
This status code indicates that the server is denying access to the resource as a consequence of a legal demand.
The server in question might not be an origin server. This type of legal demand typically most directly affects the operations of ISPs and search engines.
Responses using this status code SHOULD include an explanation, in the response body, of the details of the legal demand: the party making it, the applicable legislation or regulation, and what classes of person and resource it applies to. For example:
HTTP/1.1 451 Unavailable For Legal Reasons
Link: <https://spqr.example.org/legislatione>; rel="blocked-by"
Content-Type: text/html
<html>
<head><title>Unavailable For Legal Reasons</title></head>
<body>
<h1>Unavailable For Legal Reasons</h1>
<p>This request may not be serviced in the Roman Province of Judea due to the Lex Julia Majestatis, which disallows access to resources hosted on servers deemed to be operated by the People's Front of Judea.</p>
</body>
</html>
The use of the 451 status code implies neither the existence nor nonexistence of the resource named in the request. That is to say, it is possible that if the legal demands were removed, a request for the resource still might not succeed.
Note that in many cases clients can still access the denied resource by using technical countermeasures such as a VPN or the Tor network.
A 451 response is cacheable by default, i.e., unless otherwise indicated by the method definition or explicit cache controls; see [RFC7234].
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RFC
RFC 7725
Title
An HTTP Status Code to Report Legal Obstacles
Date
February 2016
If you want to check out more status code research and definitions check my SEO glossary here.
Last month the Internet Engineering Task Force (IETF) introduced a new HTTP status code for legally-restricted resources. Ok, before you give up on reading this, writing it off as the most boring blog on the internet, I promise you it’s not quite that dry. In fact the new HTTP error code raises some interesting questions from a social responsibility / censorship and Freedom of Information perspective.
Firstly let’s get the technical part understood, it won’t take long and it’s pretty straight forward, promise.
What is a HTTP Response Code?
After receiving a request message, a server responds to the Client with a HTTP response code consisting of a number and message. The response code provides instructions to the Client (the Web browser in many cases) to do something different with the response.
Most of the time, as a user you will have no idea of this transaction because typically, if everything is fine, then a “200 OK” message is sent which basically means there are no issues. In fact any response starting with a 2xx means a success.
It’s really common for Web Masters to use HTTP response codes to redirect requests to different URLs. All 3xx codes are redirects, with 301 and 302 being the most common. Once again this process will be seamless and go unnoticed by the user.
However what users unfortunately DO see, and this can happen all too often, is the “404 Not Found” HTTP Error code which means that the requested page can’t be found. Any 4XX code relates to a client error. But the jackpot of all errors has to be the “500 Internal Server Error” which means that the site you are trying to visit is broken in some way.
All these codes are pretty techie but having an understanding of them can be very useful, increasingly so for web teams and marketers where the responsibility for website performance seems to be shifting from technical support to marketing departments. In fact we have many clients using the traffic rule builder feature on the edgeNEXUS load balancer to change and manipulate HTTP Response codes on the fly, achieving some really useful results for superb user experience. (More on this shameless plug later.)
So what’s the New 451 Error Code All About?
Introducing “Error 451 Unavailable for Legal Reasons”, the new code for censorship. When I first saw this I didn’t actually believe it was real.
The 451 HTTP Response Code is used where the content IS accessible……but not to you – sorry! It can be used to provide transparency in circumstances where issues of law or public policy affect server operations. Courts can require ISPs to block access to certain websites, making it clear for instance when a website has been blocked after a court order.
This essentially adds a censorship mechanism to the underlying protocol that powers our open and free internet. But what I find slightly amusing about this is that it’s already happening and has been for some time. Before the introduction of the 451 HTTP Response Code, users would just experience it in a less transparent way (probably receiving a 404 error).
It’s interesting to consider the implications of this on a wider social scale, especially in relation to the behaviour of groups renowned for administering mass censorship, including governments who I will not name – oh ok China, North Korea etc. Will these bodies take advantage of the 451 HTTP Response Code for their benefit? At least the transparency of the Response Code means that users will know who to blame when they can’t access to a site.
It’s no coincidence that the new error’s number, 451, is a reference to the 1953 dystopian novel Fahrenheit 451 (named after the auto-ignition temperature of paper), addressing issues of censorship by being set in a world where books are outlawed. It seems as though even the IETF have a sense of humour when it comes to publicising the Response Code.
With a desire to look at all things on balance, there are potentially a few use cases where the 451 HTTP Response Code could be a useful tool. Take gambling for instance, where many countries have an outright ban on online betting, making it the website owner’s responsibility to block access for particular countries. Perhaps the 451 HTTP Response code can be used in this capacity, potentially blocking specific areas rather than the whole site i.e. allow sportsbook but not casino.The same applies to sites with adult content and alcohol where the user fails an age check.
With this in mind, I’m sure there are further use cases, and knowing that the code is here to stay, I guess it’s important to extrapolate as much value as possible. It’s happening anyway so at least it’s more transparent.
Ok now we’ve got the blog out of the way, here’s the product pitch that I promised you!
edgeNEXUS advanced Load Balancers feature a pretty cool rule engine that allows users to create bespoke traffic policies to deal with real world business problems. The edgeNEXUS team use this in-house to solve these type of issues.
- Prevent users from being served bad error codes (404’s etc) and the site being penalised from poor search engine results.
- Redirect pages for certain URLs based on location, browser, IP or cookie.
- Change any of the HTTP headers or even the content – why not use the new 451 HTTP Response Code to “censor” certain pages for certain countries?
- Automatically insert code snippets to pages on-the-fly, including Google Analytics page tracking code.