Explanation

XWiki applies the pending database schema updates and data migrations when it starts, provided migrations are enabled in the xwiki.cfg file. They are enabled in the configuration XWiki ships, but are commonly disabled in production for a faster startup, so check the setting before upgrading. In the # Data migrations and schema updates section, verify that the following line is present and not commented out:

xwiki.store.migration=1

FAQ

What if the migration of the database fails?

If the migration process fails, drop the DATABASECHANGELOG and DATABASECHANGELOGLOCK tables from your database and then restart the migration. This should allow the migration to proceed without further issues.