Website hosted in Plesk server is not accessible under heavy load: mod_fcgid: can't apply process slot for /var/www/cgi-bin/cgi_wrapper/cgi_wrapper

Plesk for Linux

Applicable to:

Website hosted in Plesk server is not accessible under heavy load with the following error in Apache /var/www/vhosts/example.com/logs/error_log file:
CONFIG_TEXT: mod_fcgid: can't apply process slot for /var/www/cgi-bin/cgi_wrapper/cgi_wrapper
Increasing of the FastCGI limits in accordance with the following article does not fix the issue:

Some websites are unavailable: mod_fcgid: can't apply process slot for /var/www/cgi-bin/cgi_wrapper/cgi_wrapper
A website is not accessible with "504 Gateway Time-out": The timeout specified has expired: [client 203.0.113.2:54693] AH01075: Error dispatching request to

CPU usage for the subscription is insufficient and causes requests time out

Increase Cgroup memory limits:

For Plesk Cgroups Manager extension

Log into Plesk
To increase limits for all subscriptions under a service plan, navigate to Service Plan > Default Domain > RAM, CPU, DISK I/O.

For a single subscription, navigate to Subscriptions > example.com > Customize > RAM, CPU, DISK I/O
Below secion RAM, increase value of Limit or enable checkbox Unlimited
Click Apply

Additional information can be found in (Plesk for Linux) Cgroups Manager documentation.

For custom Cgroups implementation

Custom Cgroups implementation is for example CloudLinux LVE.

Its limits can be adjusted using CloudLinux LVE Manager Plesk extension.
For information and assistance contact CloudLinux Support at https://www.cloudlinux.com/support.