Unable to export mysql database: Unable to backup database 'db' (Error code 21)

Symptoms

• Unable to export mysql database in Domains > example.com > Databases > Export Dump

  CONFIG_TEXT: Unable to export a dump of db:
  Unable to backup database 'db'
  (Error code 21)

• Client's MySQL server is version 5.1

• Migration fails with error:

  CONFIG_TEXT: Failed to copy content of database 'db'
  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: C:\Program Files (x86)\Plesk\MySQL\bin\mysqldump -h localhost -P 3306 -uadmin -p*hidden* db --result-file=C:\plesk_migrator\db_backup_example.com_db.sql --routines --events
  exit code: 2

• Database dump created with following command is empty:

  C:\> "C:\Program Files (x86)\Plesk\MySQL\bin\mysqldump" -h localhost -P 3306 -uadmin -p"admin_password" db --result-file=C:\plesk_migrator\db_backup_example.com_db.sql

Cause

The issue is related to the bug PPP-49157: "Unable to export MySQL 5.1 database: Error code 21".

Resolution

Until the bug is resolved the issue can be worked around with these steps:

1. Login to the server via RDP

2. Add default-character-set=latin1 to [client] section in C:\Program Files (x86)\Plesk\MySQL\my.ini

   CONFIG_TEXT: [client]
   port=8306
   default-character-set=latin1

3. Restart Plesk SQL Server in Windows > Services > Plesk SQL Server > Restart