MySQL reports the error on a Plesk for Linux server: Cannot load from mysql.<table_name>. The table is probably corrupted

Symptoms

• Plesk upgrade fails/completes with the following message:PLESK_ERROR: ERROR while trying to upgrade APSC SQL database from 11.1.0
  Check the error reason(see log file: /var/log/plesk/install/plesk_17.5.3_installation.log), fix and try againIn the mentioned above logfile, the following error message can be found:

  ERROR 1548 (HY000) at line 67: Cannot load from mysql.proc. The table is probably corrupted
  ...
  mysqldump: Couldn't execute 'SHOW VARIABLES LIKE 'gtid_mode'': Native table 'performance_schema'.'session_variables' has the wrong structure (1682)

• Migration completes with the following warning:PLESK_INFO: [Migration] Failed to copy content of database ‘DB_NAME’
  Migration tools tried to perform operation in 3 attempts: Command execution failed on the source server ‘source’ (203.0.113.2) with non-zero exit code.
  command: MYSQL_PWD=”$(cat)” mysqldump -h localhost -P 3306 -uadmin –quick –quote-names –add-drop-table –default-character-set=utf8 –set-charset –routines hardcore > /tmp/db-dumps/DB_NAME.sql
  exit code: 2
  stdout:
  stderr: mysqldump: Couldn’t execute ‘SHOW FUNCTION STATUS WHERE Db = ‘DB_NAME”: Cannot load from mysql.proc. The table is probably corrupted (1548)
• A backup process completes with the following warning:PLESK_INFO: Warning : mysql “Database”Not all the data was backed up into /var/lib/psa/dumps/…./databases/Database successfully. mysqldump: Couldn’t execute ‘SHOW FUNCTION STATUS WHERE Db = ‘Database”: Cannot load from mysql.proc. The table is probably corrupted (1548)
• Operations on databases in phpMyAdmin fails with:PLESK_INFO: Errors occurred while executing: mysqldump: Couldn’t execute ‘SHOW FUNCTION STATUS WHERE Db = ‘db_name”: Cannot load from mysql.proc. The table is probably corrupted (1548)
• The following error message appears in Plesk at Tools & Settings > Database Servers:PLESK_ERROR: Error: Cannot load from mysql.user. The table is probably corruptedand the MySQL (localhost) status icon is grayed out

Cause

The mysql.<table_name> table is broken or the structure of a column in the table is incorrect.

Resolution

1. Connect to the Plesk server via SSH.
2. Repair the broken table:
   • If mysql.proc is corrupted:# MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -uadmin mysql -Ne”REPAIR TABLE mysql.proc”
     +————+——–+——–+—-+
     | mysql.proc | repair | status | OK |
     +————+——–+——–+—-+
   • If mysql.user is corrupted:# MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -uadmin mysql -Ne”REPAIR TABLE mysql.user”
     +————+——–+——–+—-+
     | mysql.user | repair | status | OK |
     +————+——–+——–+—-+
3. Upgrade MySQL system tables:# MYSQL_PWD=`cat /etc/psa/.psa.shadow` /usr/bin/mysql_upgrade –force -uadmin –upgrade-system-tables
4. Restart the MySQL service. The command depends on installed MySQL server and operating system:# service mysql restart# service mariadb restart