Migration of a MySQL database fails in Plesk: Unknown collation: ‘utf8mb4_unicode_520_ci’

Symptoms

• Unable to migrate a database. The following error is displayed in Plesk:

  PLESK_INFO: Failed to copy content of database ‘wordpress_v’
  Migration tools tried to perform operation in 1 attempts: Restoration of MySQL database failed. Most probable reason:

  Target MySQL server does not contain necessary character set.
  Most likely it is required to have at least MySQL 5.5 to restore such database.
  …
  Here is the original error message reported by MySQL client when restoring the database:
  ERROR 1273 (HY000) at line 213: Unknown collation: ‘utf8mb4_unicode_520_ci’

• The collation mentioned in the error message is not available in MySQL on the destination server:

  # plesk db -e “show collation” | grep utf8mb4_unicode_520_ci
  #

Cause

On the target server, MySQL can not install the required collation.

Resolution

Apply one of the following solutions:

• Upgrade MariaDB to version 10.1 or 10.2 on the destination server. For instructions, visit this KB article.

• Migrate the subscription to the destination server with the same MySQL version as on the source server.