'ESRI.ArcGIS.Client.Tasks.ServiceException' cannot be serialized

  I experienced with a workflow error.  It is very hard to reproduce. But it may happen sometimes. Any ideas?

 I just use a query task. And I can not catch that exception in workflow.

Abortion exception: 'ESRI.ArcGIS.Client.Tasks.ServiceException' cannot be serialized. Consider marking it

 

with the DataContractAttibute attribute, and marking all of its members you want serailized with

 

DataMemberAttribute attribute