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

Symptoms

• Attempt to connect/drop psa database hangs
• mysql_upgrade hangs in the middle
• It is not possible to start migration with the following error:
  

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

• /var/log/mysql/mysql.log contains following records:
  

  [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

Corrupted database performance_schema.

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 service:
   

   # service mysql restart

4. Run mysql_upgrade once more
   

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

5. Connect to psa database:
   

   # plesk db