Today got this error through our support:
Juvander.MercuryLib.Utilities.JuvanderException (:0) - Exception: SetDefectFieldValues
Juvander.MercuryLib.Utilities.JuvanderException: SetDefectFieldValues ---> System.Runtime.InteropServices.COMException (0x800403EA): Failed to Post Bug
at QC9APIOLELib.IBug.Post()
at Juvander.MercuryLib.Data.MercuryDefectClass.Post()
Exception is coming directly from Quality Center API, but its root cause is not that clear.
This turned out to be too short field on Quality Center project, so it was trying to update value from TFS workitem which did not fit into the specified field.
Fix was to make this field bigger in Quality Center project customizations.