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WCF Exception Shielding Error

While using the WCF Exception Shielding policy in Enterprise Library’s Exception Handler Block to shield exceptions and return Fault Contracts I came across an error. I named the shielding policy “WCF Shielding Policy” and implemented a FaultContract for each type of desired or expected exception.

While testing the policy, we were unable to return a proper FaultContract from the WCF Service.  The only error that we received was the generic Communication Error:

System.ServiceModel.CommunicationException: An error occurred while receiving the HTTP response to (path of service).
 This could be due to the service endpoint binding not using the HTTP protocol.
This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down).
See server logs for more details. --->  System.Net.WebException: The underlying connection was closed:
An unexpected error occurred on a receive.
  System.IO.IOException: Unable to read data from the transport connection: An existing connection was
forcibly closed by the remote host.
 System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host.

This error is incredibly deceiving and led to many dead ends while trying to track down the root cause of the error. I re-wrote the app.config file and removed and re-added the service references, all to no avail.

The cause of the problem was simply in the name of the policy. If you don’t name your shielding policy “WCF Exception Shielding” verbatim then the policy will not be found and the error above will be thrown.  If you do name your policy something different or you implement different policies for different types of exceptions then you have to explicitly state in the ExceptionShielding attribute the name of the policy as follows:

VB: <ExceptionShielding ("MyPolicy")>

I renamed the policy to the default name and started receiving the Fault Contracts as expected.

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1 Comment. Leave new

Remote labs
April 5, 2011 2:42 am

Thank you for getting this headache away from me. You’re generous enough to have this posted.

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