php return 500 error but no error log

问题:

I am having an issue when I have a php application that is returning an internal server error (500) however nothing is showing up in the error log.

Now I know there are error with what I am trying to run, I know I have missing some files and what not but something should show in the apache error log (otherwise how are I supposed to know exactly what I am missing).

I created a test script is errors it in under the same vhost configuration and those error show up fine so everything seems configured right as far as php/apache. Are there certain php errors that does show up in the error log (php is configure to display any type of notice, warning, , error, fatal error, etc...)?

This is running on ubunut 10.04 with the standard apache and php from the ubuntu repo with apt-get.

回答1:

Scan your source files to find @.

From php documentation site

Currently the "@" error-control operator prefix will even disable error reporting for critical errors that will terminate script execution. Among other things, this means that if you use "@" to suppress errors from a certain function and either it isn't available or has been mistyped, the script will die right there with no indication as to why.

回答2:

Maybe something turns off error output. (I understand that you are trying to say that other scripts properly output their errors to the errorlog?)

You could start debugging the script by determining where it exits the script (start by adding a echo 1; exit; to the first line of the script and checking whether the browser outputs 1 and then move that line down).

回答3:

Copy and paste the following into a new .htaccess file and place it on your website's root folder :

php_flag  display_errors                  on
php_flag  display_startup_errors          on

Errors will be shown directly in your page.

That's the best way to debug quickly but don't use it for long time because it could be a security breach.

回答4:

In the past, I had no error logs in two cases:

1. The user under which Apache was running had no permissions to modify php_error_log file.
2. Error 500 occurred because of bad configuration of .htaccess, for example wrong rewrite module settings. In this situation errors are logged to Apache error_log file.

回答5:

For Symfony projects, be sure to check files in the project'es app/logs

More details available on this post :
How to debug 500 Error in Symfony 2

Btw, other frameworks or CMS share this kind of behaviour.

回答6:

Here is another reason why errors might not be visible:

I had the same issue. In my case, I had copied the source from a production environment. Hence the ENVIRONMENT variable defined in index.php was set to 'production'. This caused error_reporting to be set to 0 (no logging). Just set it to 'development' and you should start seeing error messages in apache log.

Turned out the 500 was due to a semi colon missing in database config :-)

回答7:

Another case which happened to me, is I did a CURL to some of my pages, and got internal server error and nothing was in the apache logs, even when I enabled all error reporting.

My problem was that in the CURL I set curl_setopt($CR, CURLOPT_FAILONERROR, true);

Which then didn't show me my error, though there was one, this happened because the error was on a framework level and not a PHP one, so it didn't appear in the logs.

回答8:

You need to enable the PHP error log.

This is due to some random glitch in the web server when you have a php error, it throws a 500 internal error (i have the same issue).

If you look in the PHP error log, you should find your solution.

see here in the doc of how to enable it in the php.ini

回答9:

Be sure your file permissions are correct. If apache doesn't have permission to read the file then it can't write to the log.

回答10:

If you still have 500 error and no logs you can try to execute from command line:

php -f file.php

it will not work exactly like in a browser (from server) but if there is syntax error in your code, you will see error message in console.

回答11:

What happened for me when this was an issue, was that the site had used too much memory, so I'm guessing that it couldn't write to an error log or displayed the error. For clarity, it was a Wordpress site that did this. Upping the memory limit on the server showed the site again.