Administration - Installation - Core: Behaviour of ECS Task Scheduler

Hi,

I made a copy of our ILIAS production environment containing lots of remote ECS courses and connected this copy with a new ECS server. Now in ilias.log I see an ECS task scheduler obviously deleting obsolete remote courses and their references:

[u17j9] [2019-07-18 17:10:44.771898] ecampus_root.INFO: ilRemoteObjectBase::handleDelete:272 ilRemoteObjectBase::handleDelete: Deleting obsolete remote course: Graduiertenkolleg 1878 "Archäologie vormoderner Wirtschaftsräume"
[u17j9] [2019-07-18 17:10:44.772784] ecampus_root.INFO: ilObject::delete:218 ilObject::delete(), object not deleted, number of references: 3, obj_id: 757970, type: rcrs, title: Graduiertenkolleg 1878 "Archäologie vormoderner Wirtschaftsräume"
...

Is this some sort of "garbage collector" deleting ECS courses imported from an ECS server not known to ILIAS anymore? When and how is it triggered?

It would be nice if someone could explain what is going on behind the scenes in this case. When this scheduler is running, calling any ILIAS page leads to the error message "ilTree::getNodeData(): No node_id given!" and you'll have to go back to the repository - which is not very nice behaviour ;-)

Best regards
Carsten