We just did an upgrade of an old site from 1.6 via 2.0 to 2.1.
Some of the “File group …” service checks started to complain that they did not find a group_pattern.
They were so old that their service discovery did not add that to the service’s inventorized parameters.
A new service discovery was necessary to fix that. We found no “incompatible” werk that documents this.
Second, we had an exisiting “File group …” service check where the “Group patterns” rule was changed after its discovery. The service check still uses the older pattern until a new service discovery has been done. This is also not stated anywhere. When changing or adding a new rule in “Group patterns” the GUI should remind you that you need to do a new service discovery (tabula rasa) on the affected host(s).