If you click the signpost "Where Am I?" icon from the toolbar when viewing an Incident (or Problem, Task etc) you receive the following error:
System.FormatException: Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).
Open the process in Process Designer and check its validity. Make sure there are no actions that shouldn't be there or aren't linked to anything else. Fix these then re-save/re-activate the process.