Symptoms
Web Hosting Plesk module Websites Manager Node becomes unavailable over API with the following error appearing in /var/log/httpd/error_log:
AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting
The node is deployed inside a Virtuozzo Container.
The following configuration is present:
# grep MaxClients /etc/httpd/conf.d/mpm_prefork.conf
MaxClients 10
Cause
Incorrect extra Apache configuration file appears in case the node is deployed in a Virtuozzo Container.
Resolution
Remove the configuration file for Apache MPM Prefork module and restart the service:
# rm -f /etc/httpd/conf.d/mpm_prefork.conf
# systemctl restart httpd