Cron job throws frequently errors

Linux: x86_64-redhat
Apache: 2.4.37
PHP: 7.1.26 fpm
SQL: 10.3.12-MariaDB

Installation was migrated from Uberspace 6 to Uberspace 7 acc. to Migrating ownCloud from uberspace 6 to uberspace 7

Redis not running (as no php-redis module is yet available - acc. to uberspace support)

cron delivers erratic:

PHP Fatal error:  Uncaught PDOException: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when trying to get lock; try restarting transaction in [path to owncloud]/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php:105
Stack trace:
#0 [path to owncloud]/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php(105): PDOStatement->execute(NULL)
#1 [path to owncloud]/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(1006): Doctrine\DBAL\Driver\PDOStatement->execute()
#2 [path to owncloud]/lib/private/DB/Connection.php(207): Doctrine\DBAL\Connection->executeUpdate('UPDATE `oc_file...', Array, Array)
#3 [path to owncloud]/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Query/QueryBuilder.php(208): OC\DB\Connection->executeUpdate('UPDATE `oc_file...', Array, Array)
#4 [path to owncloud]/lib/private/DB/QueryBuilder/QueryBuilder.php(141): Doctrin in /var/www/virtual/whoamu/ on line 115

any idea how to tackle this?

best regards Stefan

ideas anyone?
regard Stefan


i did the following search:

and found a few (sometimes still open) issues about this message. Maybe those contains some additional information?

just migrated a owncloud instance from PHP5.6 to 7.x (tryied: 7.0 7.1 and 7.2) and got similar messages.

Could this be the reason for the error messages: