mysql_upgrade — Check and Upgrade MySQL Tables After running  mysql_tzinfo_to_sql , it is best to restart the server so that it does not continue to use any previously cached time zone data. 4.4.5 mysql_upgrade — Check and Upgrade MySQL Tables Note As of MySQL 8.0.16, the MySQL server performs the upgrade tasks previously handled by  mysql_upgrade  (for details, see Section 2.11.3, “What the MySQL Upgrade Process Upgrades” ). Consequently,  mysql_upgrade  is unneeded and is deprecated as of that version; expect it to be removed in a future version of MySQL. Because  mysql_upgrade  no longer performs upgrade tasks, it exits with status 0 unconditionally. Each time you upgrade MySQL, you should execute  mysql_upgrade , which looks for incompatibilities with the upgraded MySQL server: •It upgrades the system tables in the  mysql  schema so that you can take advantage of new privileges or capabilities that might have been added. •It upgrades the Performance Schema,  INFORMATION_SCHEMA , and  sys  schema. •It examines user schemas. If  mysql_upgrade  finds that a table has a possible incompatibility, it performs a table check and, if problems are found, attempts a table repair. If the table cannot be repaired, see Section 2.11.13, “Rebuilding or Repairing Tables or Indexes”  for manual table repair strategies. mysql_upgrade  communicates directly with the MySQL server, sending it the SQL statements required to perform an upgrade. Caution You should always back up your current MySQL installation  before  performing an upgrade. See Section 7.2, “Database Backup Methods” . Some upgrade incompatibilities may require special handling  before  upgrading your MySQL installation and running  mysql_upgrade . See Section 2.11, “Upgrading MySQL” , for instructions on determining whether any such incompatibilities apply to your installation and how to handle them. Use  mysql_upgrade  like this: 1. Ensure that the server is running. 2. Invoke  mysql_upgrade  to upgrade the system tables in the  mysql  schema and check and repair tables in other schemas: 3. Stop the server and restart it so that any system table changes take effect. mysql_upgrade [ options ] If you have multiple MySQL server instances to upgrade, invoke  mysql_upgrade  with connection parameters appropriate for connecting to each of the desired servers. For example, with servers running on the local host on parts 3306 through 3308, upgrade each of them by connecting to the appropriate port: mysql_upgrade --protocol=tcp -P 3306 [ other_options ] mysql_upgrade --protocol=tcp -P 3307 [ other_options ] mysql_upgrade --protocol=tcp -P 3308 [ other_options ] 404