Attempt to connect or drop psa database hangs: Native table 'performance_schema'.'session_variables' has the wrong structure

Symptoms

• Attempt to connect to or drop psa database hangs

• mysql_upgrade hangs in the middle

• It is not possible to start migration with the following error:

  Native table 'performance_schema'.'session_variables' has the wrong structure

• /var/log/mysql/mysql.log contains errors like the following:

  [ERROR] Native table 'performance_schema'.'events_waits_current' has the wrong structure
  [ERROR] Native table 'performance_schema'.'events_waits_history' has the wrong structure
  <lots of entries>
  [ERROR] Native table 'performance_schema'.'cond_instances' has the wrong structure
  [ERROR] Native table 'performance_schema'.'file_instances' has the wrong structure

Cause

Database performance_schema is corrupted.

Resolution

1. Connect to the server via SSH

2. Run mysql_upgrade (if it hangs, cancel it):

   # MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql_upgrade -uadmin --force

3. Restart MySQL/MariaDB:

   # systemctl restart mariadb

4. Run mysql_upgrade once more

   # MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql_upgrade -uadmin --force

5. Connect to psa database:

   # plesk db