LogicException: The database connection is not serializable.

Beim Anlegen eines neuen Term Reference Feldes, erhalte ich auf dem Field Config Form den (Ajax) Fehler:

LogicException: The database connection is not serializable.
This probably means you are serializing an object that has an indirect reference to the database connection.
Adjust your code so that is not necessary. Alternatively, look at DependencySerializationTrait as a temporary solution.
in Drupal\Core\Database\Connection->__sleep() (line 1920 of /var/www/html/web/core/lib/Drupal/Core/Database/Connection.php).

Wenn ich sites_group_overrides deaktiviere, kommt der Fehler nicht.

Benutzung des DependencySerializationTrait in den FormDecorator Classes ConfigFields und TargetConfigFields scheint das Problem zu beheben.