Plesk is not accessible and MariaDB fails to start: Failed with result 'oom-kill'.

Symptoms

• Plesk is inaccessible

  Server Error
  500 Plesk\Exception\Database 
  DB query failed: SQLSTATE[HY000] [2002] Connection refused

• The MariaDB logs show that the process was terminated by the out-of-memory (OOM) killer

  # journalctl -xeu mariadb.service
  The process' exit code is 'killed' and its exit status is 9. 
  mariadb.service: Failed with result 'oom-kill'. 
  Subject: Unit failed

• The system has no swap configured or is running out of memory

  # free -h
  total used free shared buff/cache available 
  Mem: 1.8Gi 796Mi 158Mi 236Mi 908Mi 646Mi 
  Swap: 0B 0B 0B

Cause

The server doesn't have enough free memory for MariaDB, so it terminates the process to prevent a server crash.

Resolution

To fix the problem, more memory needs to be made available to MariaDB. Some options are:

Note: Reach out to the hosting provider or system administrator if assistance is needed with these steps

• Configure swap to use as backup memory: How to create a swap file on a Plesk Linux
• Increase the amount of RAM on the server