Internal Error 500 Apache but nothing in the logs

Question

I m getting 500 Internal Server errors when I try to make an HTTP POST to a specific address in my app   I ve looked into the server logs in the custom log directory specified in the virtual hosts file  but the error doesn t show up there so debugging this has been a pain in the ass   How do I cause Apache to log Internal 500 errors into the error log

User · Answer

Please check if you are disable error reporting somewhere in your code.

There was a place in my code where I have disabled it, so I added the debug code after it:

require_once("inc/req.php");   <-- Error reporting is disabled here

// overwrite it
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

User · Answer

Why are the 500 Internal Server Errors not being logged into your apache error logs  The errors that cause your 500 Internal Server Error are coming from a PHP module   By default  PHP does NOT log these errors   Reason being you want web requests go as fast as physically possible and it s a security hazard to log errors to screen where attackers can observe them  These instructions to enable Internal Server Error Logging are for Ubuntu 12 10 with PHP 5 3 10 and Apache 2 2 22  Make sure PHP logging is turned on   Locate your php ini file  el apollo    locate php ini  etc php5 apache2 php ini   Edit that file as root  sudo vi  etc php5 apache2 php ini   Find this line in php ini  display errors   Off   Change the above line to this  display errors   On   Lower down in the file you ll see this   display startup errors     Default Value  Off     Development Value  On     Production Value  Off   error reporting     Default Value  E ALL  amp   E NOTICE     Development Value  E ALL   E STRICT     Production Value  E ALL  amp   E DEPRECATED   The semicolons are comments  that means the lines don t take effect   Change those lines so they look like this  display startup errors   On     Default Value  Off     Development Value  On     Production Value  Off  error reporting   E ALL     Default Value  E ALL  amp   E NOTICE     Development Value  E ALL   E STRICT     Production Value  E ALL  amp   E DEPRECATED  What this communicates to PHP is that we want to log all these errors   Warning  there will be a large performance hit  so you don t want this enabled on production because logging takes work and work takes time  time costs money   Restarting PHP and Apache should apply the change   Do what you did to cause the 500 Internal Server error again  and check the log  tail -f  var log apache2 error log   You should see the 500 error at the end  something like this   Wed Dec 11 01 00 40 2013   error   client 192 168 11 11  PHP Fatal error    Call to undefined function Foobar  byob  penguin  alert   in  yourproject  your src symfony Controller MessedUpController php on line 249  referer   https   nuclearreactor com abouttoblowup

User · Answer

Check that the version of php you re running matches your codebase  For example  your local environment may be running php 5 4  and things run fine  and maybe you re testing your code on a new machine that has php 5 3 installed  If you are using 5 4 syntax such as    for array   then you ll get the situation you described above

User · Answer

I just ran into this and it was due to a mod authnz ldap misconfiguration in my  htaccess file   Absolutely nothing was being logged  but I kept getting a 500 error   If you run into this particular issue  you can change the log level of mod authnz ldap like so   LogLevel warn authnz ldap module debug   That will use a log level of debug for mod authnz ldap but warn for everything else  https   httpd apache org docs 2 4 en mod core html loglevel

User · Answer

The answers by  eric-leschinski is correct   But there is another case if your Server API is FPM FastCGI  Default on Centos 8 or you can check use phpinfo   function   In this case     Run phpinfo   in a php file  Looking for Loaded Configuration File param to see where is config file for your PHP  Edit config file like  eric-leschinski  s answer  Check Server API param   If your server only use apache handle API -  restart apache  If your server use php-fpm you must restart php-fpm service     systemctl restart php-fpm   Check the log file in php-fpm log folder   eg  var log php-fpm www-error log

User · Answer

Add HttpProtocolOptions Unsafe to your apache config file and restart the apache server  It shows the error details

User · Answer

Try accessing a static file  If this is not working either then  go to all directories from the root     or  c    to the directory of your file and check if they contain   htaccess  files   I once left a file in  c    and it had the most strange results

User · Answer

Check your php error log which might be a separate file from your apache error log   Find it by going to phpinfo   and check for error log attribute  If it is not set   Set it  https   stackoverflow com a 12835262 445131  Maybe your post max size is too small for what you re trying to post  or one of the other max memory settings is too low

User · Answer

In my case it was the ErrorLog directive in httpd conf  Just accidently noticed it already after I gave up  Decided to share the discovery   Now I know where to find the 500-errors

User · Answer

If your Internal Server Error information doesn t show up in log files  you probably need to restart the Apache service   I ve found that Apache 2 4  at least on Windows platform  tends to stubbornly refuse to flush log files   instead  logged data remains in memory for quite a while  It s a good idea from the performance point of view but it can be confusing when developing

User · Answer

Please Note  The original poster was not specifically asking about PHP  All the php centric answers make large assumptions not relevant to the actual question   The default error log as opposed to the scripts error logs usually has the  more  specific error  often it will be permissions denied or even an interpreter that can t be found   This means the fault almost always lies with your script  e g you uploaded a perl script but didnt give it execute permissions  or perhaps it was corrupted in a linux environment if you write the script in windows and then upload it to the server without the line endings being converted you will get this error   in perl if you forget   print  content-type  text html r n r n     you will get this error  There are many reasons for it  so please first check your error log and then provide some more information   The default error log is often in  var log httpd error log or  var log apache2 error log   The reason you look at the default error logs  as indicated above  is because errors don t always get posted into the custom error log as defined in the virtual host   Assumes linux and not necessarily perl

[apache] Internal Error 500 Apache, but nothing in the logs?

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