Cannot load from mysql.proc.

Symptoms

Plesk upgrade fails with the following error:

ERROR while trying to upgrade APSC SQL database from 11.1.0

The following error can be found in /tmp/plesk_11.5.30_installation.log or /tmp/autoinstaller3.log file:
```
ERROR 1548 (HY000) at line 67: Cannot load from mysql.proc. The table is probably corrupted
```

Attempt to drop a procedure (even if it does not exist) fails:

mysql> DROP PROCEDURE IF EXISTS test1234;
ERROR 1548 (HY000): Cannot load from mysql.proc. The table is probably corrupted

In /var/log/mysqld.log the following errors can be found:

# grep ERROR /var/log/mysqld.log
[ERROR] Missing system table mysql.proxies_priv; please run mysql_upgrade to create it
.....
[ERROR] Native table 'performance_schema'.'events_waits_current' has the wrong structure
[ERROR] Native table 'performance_schema'.'events_waits_history' has the wrong structure
.....
[ERROR] Incorrect definition of table mysql.proc: expected column 'comment' at position 15 to have type text, found type char(64).

Cause

The structure of the mysql tables is incorrect or has not been upgraded.

Resolution

Make sure mysql database is not corrupted with the mysqlcheck command:

# MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysqlcheck -uadmin mysql
mysql.columns_priv                                 OK
mysql.db                                           OK
.....
mysql.time_zone_transition_type                    OK
mysql.user                                         OK

Repair the table if necessary:

# MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -uadmin mysql -Ne"REPAIR TABLE mysql.proc"
+------------+--------+----------+----------+
| Table      | Op     | Msg_type | Msg_text |
+------------+--------+----------+----------+ 
| mysql.proc | repair | status   | OK       |
+------------+--------+----------+----------+

Change the type of proc.comment row as below:

# MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql -uadmin mysql -Ne"alter table proc change comment comment text"
Query OK, 0 rows affected (0.01 sec)Records: 0 Duplicates: 0 Warnings: 0

Upgrade MySQL server:

# MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql_upgrade -u admin
Looking for 'mysql' as: mysql
Looking for 'mysqlcheck' as: mysqlcheck
Running 'mysqlcheck with default connection arguments
Running 'mysqlcheck with default connection arguments
apsc.aps_application                               OK
apsc.aps_application_backup                        OK
....
mysql.columns_priv                                 OK
mysql.db                                           OK
....
psa.Configurations                                 OK
psa.DashboardPreset                                OK
....
Running 'mysql_fix_privilege_tables'...
OK

Fuente support.plesk.com