Where are the PHP error messages (error_log) stored?

If enabled, Apache stores all PHP error messages of your website in a separate log file. This includes warnings, hints and also errors, depending on which log level you have defined before. Beside the standard locations for the error.log you can also define an individual location, for example with PHP, you can find more about that here.

On Linux, Apache places the error.log file here:

/var/log/apache2/error.log

Alternatively you can find the error messages here:

/var/www/vhosts/system/{domain}/logs/error_log