Htaccess ошибка 500 редирект

but when I encounter a 500 Internal Server Error, it gives the default Internal Server Error

The problem is that custom 500 error documents defined «late» in .htaccess simply don’t get triggered for the majority of server errors — which is what’s likely happening here. As Aakash has already quoted, this may come under the realm of a «malformed request». If you check your error log it should state: «core:error».

You stand a better chance of the custom 500 error document being served if it is defined «early» in the main server config (or VirtualHost container).

In fact, it is a bit tricky to simulate a real error that will trigger the custom 500 error document defined in .htaccess.

However, you can manually trigger a 500 error, which will call your custom error handler with something like the following:

RewriteCond %{ENV:REDIRECT_STATUS} ^$
RewriteRule ^ - [R=500]

The check against the REDIRECT_STATUS env var ensures that the internal request for the error document itself does not trigger another 500 error, but a direct request for the error document would also trigger a 500 error. This check is not necessary if you already have an exception in place for error documents.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

This does literally mean that in addition to the 500 error that resulted from the initial request, another 500 error was encountered when trying to serve the custom error document (that is called via an internal subrequest).

The custom error document itself is also processed by the Apache config/.htaccess.

Generally, exceptions need to be made for custom error documents so they can be served without additional processing.

More info: I can get it to throw 500 if I type a trailing slash on a .html page that has had the «.html» removed…

Not sure that this is really part of your question, but this 500 error is the result of a rewrite loop. Specifically:

RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^(.+)$ $1.html [L,QSA]

Request: http://example.com/test/ (with the extra slash)

In this case the %{REQUEST_FILENAME} is /path/to/test (no trailing slash), so the condition %{REQUEST_FILENAME}.html -f is true (/path/to/test.html does exist).

However, the URL-path that is captured by the RewriteRule pattern does contain the trailing slash ie. test/ — it is not the same as the REQUEST_FILENAME in this instance. So the URL gets incorrectly rewritten to test/.html.

And the rewriting starts over again from the top (because the URL has changed)… test/.html.html, test/.html.html.html, etc. (Because the REQUEST_FILENAME is always /path/to/test.)

Yes, there is a rewrite loop for every URI coming from a subdomain here that doesn’t map to a filename or directory.

For example if the client comes in with mail.indst.eu/nofile

• Hit subdomain rule mail.indst.eu for condition !^/mail -> rewrite to mail.indst.eu/mail/nofile
• No longer matches !^/mail, doesn’t hit any external redirect rules, so falls through towards the end.
  • Doesn’t match the rewrite exclusion for existing files or one of the hardcoded exclusions
  • Hits the non-host-bound all-uri rule, gets rewritten to mail.indst.eu/index.php
• Now it matches again the subdomain rule mail.indst.eu for condition !^/mail -> rewrite to mail.indst.eu/mail/index.php
• No longer matches !^/mail, doesn’t hit any external redirect rules, so falls through towards the end.
• Hits the non-host-bound all-uri rule, apparently mail/index.php is not an existing file, so /mail/index.php gets rewritten to /index.php, now we are in an alternating repeat between /index.php and /mail/index.php

/nofile
/mail/nofile (does not exist)
/index.php
/mail/index.php (does not exist)
/index.php
/mail/index.php (does not exist)
...repeat last two...

If you place an index.php in the subdirectories used by the subdomains, then a non-existing file uri on a subdomain will end up at the matching subdomain/index.php files, which for some applications may be what you want.
If you want a serverlevel 404 response, then you have to exclude the subdomain hosts from the catchall rewrite to index.php.

For example

RewriteCond %{HTTP_HOST} !^mail\.indst\.eu$
RewriteCond %{HTTP_HOST} !^www\.statesanalytics\.com$
RewriteRule ^.*$ index.php [NC,L]

OR, which might be more succint, and allow more subdomains:

RewriteCond %{REQUEST_URI} !^/mail
RewriteCond %{REQUEST_URI} !^/sa
RewriteRule ^.*$ index.php [NC,L]

Then a non existing uri at mail.indst.eu/starting-path is server level non existing if it doesn’t exist in mail/starting-path

There are other techniques to prevent such loops. If you know that there would always at most be one internal redirect for example, and all rewriterules reside in this one .htaccess then you can do this as first rewriterule in your .htaccess:

RewriteCond %{ENV:REDIRECT_STATUS} !^$
RewriteRule ^(.*)$ - [L]

That stops further internal redirects from this .htaccess. But it would require you to put the external redirect rules that you have before the internal redirect rules. It would not stop the RedirectMatch rules.

Or, if you know that a catchall rewrite to index.php should always be the last word the end mod_rewrite processing with [END]. But in this case that would mean a 404 on the subdomain ends up with the main directory index.php which may not be what you want.

RewriteRule ^.*$ index.php [END]