I'm running an async GP task from a widget.. 
When one of the params given to the GP is wrong (e.g. wrong or inaccessible folder path), in the job messages I get this messages: 
- <GPMessage xsi:type="typens:GPMessage">   <MessageType>200</MessageType>
  <MessageCode>0</MessageCode>
  <MessageDesc>Cancelled script Groups Cross Section - Web...</MessageDesc>
  </GPMessage>
- <GPMessage xsi:type="typens:GPMessage">   <MessageType>200</MessageType>
  <MessageCode>0</MessageCode>
  <MessageDesc>(Groups Cross Section - Web) aborted by User.</MessageDesc>
  </GPMessage>
BUT the job status is still on executing, and won't change to failed. Which means my GP is submitting a job after a job and doesn't stop running.