Website in Plesk fails to load with error 503: Memory cgroup out of memory: Kill process

Renan Poss Moreira

Updated January 20, 2026 17:23

Plesk for Linux kb: technical ABT: Group A cloudlinux

Applicable to:

Plesk for Linux

Symptoms

The following error appears when attempting to load a file in a site:

CONFIG_TEXT: Server Error
503
Service Temporarily Unavailable
Site shows error 504 intermittently
CloudLinux operating system is used or the extension Plesk Cgroups Manager is installed
PHP-FPM pool exits after some time with the following warning found at PHP-FPM log file (/var/log/plesk-php8x-fpm/error.log):

CONFIG_TEXT: WARNING: [pool example.com] child 2920572 exited on signal 9 (SIGKILL) after 2611.194074 seconds from start
PHP-FPM pool memory errors as below examples are found at /var/log/messages:

CONFIG_TEXT: 129 kernel: Killed process 675388 (php-fpm) in VE "0" total-vm:1767832kB, anon-rss:114724kB, file-rss:11132kB, shmem-rss:12268kB
129 kernel: OOM killer in rage 0: 0 tasks killed

CONFIG_TEXT: host kernel: [6441970.759935] 2996362 (php-fpm) invoked oom-killer in ub 10061 generation 504 gfp 0x200d2

CONFIG_TEXT: host kernel: LVE: [8884] _lve_enter: Can't alloc ve #10151 lvp #0, rc -22

CONFIG_TEXT: kernel: oom_reaper: reaped process 1234 (php-fpm)

CONFIG_TEXT: host mysqld: 2020-01-11T16:03:58.979977Z 16499264 [Note] Aborted connection 16499264 to db: 'example_db' user: 'jdoe' host: 'localhost' (Got an error reading communication packets)

The following errors can be found in /var/www/vhosts/system/example.com/logs/error_log

INTERNAL: the symptoms are not unique

[proxy_fcgi:error] [pid 31123:tid 139667655595776] (70007)The timeout specified has expired: [client 203.0.113.2:57054] AH01075: Error dispatching request to :

[proxy_fcgi:error] [pid 427900:tid 140512497018624] [client 203.0.113.2:51548] AH01079: failed to make connection to backend: httpd-UDS

[proxy:error] [pid 401035:tid 140513101293312] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /var/www/vhosts/system/example.com/php-fpm.sock (*) failed

Cause

PHP-FPM process is killed by Cgroups due to reached memory limits.

Resolution

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 Plesk Cgroups integration running on CloudLinux

Limits can be adjusted using CloudLinux LVE Manager Plesk extension.

To install it, connect to the server using SSH and execute the following command:

# yum install lvemanager

After installing it, go to Plesk, then in the left-side menu click LVE Manager. For information and assistance contact CloudLinux Support at https://www.cloudlinux.com/support.