- Plesk for Linux
Switching Apache webserver to mpm_prefork mode in Home > Tools&Settings > Apache Web Server causes web server down:
# service apache2 status
apache2.service - LSB: Apache2 web server
Active: failed (Result: exit-code) since Thu 2018-01-18 17:29:21 CET; 34s ago
Jan 18 17:29:21 example.com apache2: AH00526: Syntax error on line 10 of /etc/apache2/mods-enabled/mpm_prefork.conf:
Jan 18 17:29:21 example.com apache2: Invalid command 'MinSpareThreads', perhaps misspelled or defined by a module not included in the server configuration
Jan 18 17:29:21 example.com apache2: Action 'configtest' failed.
The following error can be observed in Plesk:
PLESK_ERROR: New configuration files for the Apache web server were not created due to the errors in configuration templates: AH00526: Syntax error on line 9 of /etc/apache2/mods-enabled/mpm_prefork.conf: Invalid command 'MinSpareThreads', perhaps misspelled or defined by a module not included in the server configuration . Detailed error descriptions were sent to you by email. Please resolve the issues and click here to generate broken configuration files once again or here to generate all configuration files. See the details in Configuration Troubleshooter
/etc/apache2/mods-available/mpm_prefork.conf has directives applicable for
mpm_event mode only, e.g. MinSpareThreads directive
The Debian-like Linux distribution is installed on the server
Invalid directives in /etc/apache2/mods-available/mpm_prefork.conf configuration file.
- Connect to the server using SSH
- Review the directives inside of
/etc/apache2/mods-available/mpm_prefork.confand make that they are applicable for mpm_prefork mode. Use the Apache documentation as a reference. For example, for MinSpareThreads only event is mentioned and for StartServers event and prefork as well:
- Remove the invalid directives from the
- Check the validity of Apache configuration, it should return OK :
# apache2ctl -t
- Log into Plesk.
- Navigate Tools & Settings > Apache Web Server switch from prefork to event mode and click Apply button.
- Switch it back to prefork to rebuild all the necessary configuration files.