Update 20.0.4 critical error on mySQL

UNIX socket, MariaDB, Server: 10.2.36, Protocol 10, PHP 7.3.6, MySql 5.6.43
Update fails Integrity check with the following error code:

Doctrine\DBAL\Exception\DriverException: An exception occurred while executing ‘INSERT INTO oc_appconfig (appid,configkey,configvalue) SELECT ?,?,? FROM oc_appconfig WHERE appid = ? AND configkey = ? HAVING COUNT(*) = 0’ with params [“core”, “oc.integritycheck.checker”, “[]”, “core”, “oc.integritycheck.checker”]: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away

If I manually change out the “?” with the corresponding parameters the query works, but the integrity check fails on the same line the next time I run the updater.

It just means that you are not connected to the database server any more. Is there a timeout on the database server? Or does the database server crash? Check the logfiles of the db server.