Database importing in Plesk fails: ERROR 2006 (HY000): MySQL server has gone away

Symptoms

• Database importing via Domains > example.com > Databases > Import Dump fails:

  PLESK_ERROR: ERROR 2006 (HY000) at line 1253: MySQL server has gone away
  Traceback (most recent call last):
  File "/usr/local/psa/admin/sbin/dbbackup", line 6, in <module>
  File "/usr/local/psa/lib/modules/python/dbbackup/dbbackup.py", line 99, in main
  restore(options, password)
  File "/usr/local/psa/lib/modules/python/dbbackup/dbbackup.py", line 88, in restore
  raise Exception("program 'mysql' finished with non-zero exit code: %d" % p.returncode)
  Exception: program 'mysql' finished with non-zero exit code: 1

• Subscription migration fails:

  PLESK_ERROR: error: Failed to copy content of database 'example_db'
  Migration tools tried to perform operation in 3 attempts: Command execution failed on the local server with non-zero exit code.
  command: mysql --defaults-file=/usr/local/psa/var/modules/panel-migrator/sessions/<session-ID>/target-server/my_localhost_example_db.cnf -h localhost -P 3306 -uadmin example_db < /usr/local/psa/var/modules/panel-migrator/sessions/<session-ID>/target-server/db-dumps/example_db.sql
  exit code: 1
  stdout:
  stderr: ERROR 2006 (HY000) at line 405: MySQL server has gone away

Cause

Data string in dump is higher than max_allowed_packet default value in MySQL/MariaDB (4 MB).

Resolution

Increase the value of the MySQL/MariaDB parameter max_allowed_packet using the steps from this article.