MariaDB defaults
The bundled MariaDB 11.8 configurations explicitly set innodb_snapshot_isolation=OFF:
overrides/compose.mariadb.yamloverrides/compose.mariadb-shared.yamlpwd.ymldevcontainer-example/docker-compose.yml- The ARM64 example
MariaDB 11.8 enables this setting by default. Disabling it restores the earlier conflict-handling behavior as a compatibility workaround for Frappe concurrency errors, including Contact background jobs that fail with error 1020. This follows the defaults used by Frappe Press and Pilot.
Transactions and row locking remain enabled, but the additional snapshot write-conflict protection is disabled. This setting does not resolve the underlying application races. See issue #2043.
For existing deployments, regenerate any rendered Compose configuration and recreate the database container to apply the changed startup command. Recreating the container interrupts database connections; retain the existing database volume. External database servers are unaffected by these Compose defaults.