Error Log Fills Up Disk

The server's main stderr.log is growing very fast and is filling up the disk space rapidly, like so:

34G /var/log/apache2/stderr.log.2019_01_07
6.1G /var/log/apache2/stderr.log.2019_01_07.01
6.3G /var/log/apache2/stderr.log.2019_01_07.02
6.0G /var/log/apache2/stderr.log.2019_01_07.03
5.7G /var/log/apache2/stderr.log.2019_01_07.04
6.2G /var/log/apache2/stderr.log.2019_01_08
6.0G /var/log/apache2/stderr.log.2019_01_08.01
6.2G /var/log/apache2/stderr.log.2019_01_08.02
6.2G /var/log/apache2/stderr.log.2019_01_08.03
36G /var/log/apache2/stderr.log.2019_01_08.04
6.2G /var/log/apache2/stderr.log.2019_01_08.05
5.8G /var/log/apache2/stderr.log.2019_01_08.06
5.9G /var/log/apache2/stderr.log.2019_01_09

When you check the contents of stderr.log you see many PHP warning messages:

PHP Warning: next() expects parameter 1 to be array, null given in /home// /wp-includes/class-wp-hook.php on line 291
PHP Warning: current() expects parameter 1 to be array, null given in /home// /wp-includes/class-wp-hook.php on line 275
PHP Warning: Invalid argument supplied for foreach() in /home// /wp-includes/class-wp-hook.php on line 277
PHP Warning: next() expects parameter 1 to be array, null given in /home// /wp-includes/class-wp-hook.php on line 291

The warnings are from different shared hosting users but all are logged to the main server stderr.log log.

We believe the excessive logging is due to a PHP change. The PHP engine generates a lot of error/warning messages. So, how do you stop this?

Upgrade to the latest LSWS build (version 5.3.5 or above), navigate to LSWS Admin Panel > Server > Log and set Enable stderr Log to No. This should stop writing error output to stderr.log.

If you only want to stop PHP-related error reporting in stderr.log, you can leave Enable stderr Log set to Yes, and then add a special environment variable to LSPHP external application configuration:

LSAPI_STDERR_LOG=/dev/null

This will discard PHP-generated warning messages.