Object with ID 'XXX' and type 51 (Schedule Trigger) is not found in the metadata. It may have been deleted.
CAUSE:The second error better explains the issue at hand here. The issue is due to a particular schedule object missing from the metadata while it still has a reference to the project.
ACTION:Within a separate environment, perform a search for the object ID presented in the second error message mentioned above. The search can be performed using Strategy Desktop 9.3.0 within
Administration -> Configuration Managers -> Schedules by doing a "search by ID". If the schedule object is returned and exists within a different environment, Strategy Object Manager can then be used to migrate the object back into the problematic environment so it exists successfully.
If the reference is not found in another environment, contact Strategy Technical Support for assistance in finding the problematic reference.