The PHP error log has stopped working. It did work

It’s been working for ages and stopped. I must be missing something obvious.

File /etc/php5/apache2/php.ini relevant settings are:

display_errors = On  (I am not sure if this makes a difference)
log_errors = On
error_log = "/var/www/error_log.log"

In my code I have:

echo 'About to log';
error_log('An error');

I see “About to log” on the page, but nothing in the error log. How can I fix this?

Answer

Restart the Web server. Until you do php.ini changes are not considered.

Also, if you want to track PHP errors, you need to have track_errors=On and error_reporting=E_ALL, although that is not related with error_log calls. Also make sure that the error log file is writeable by the Web server user.