Question

I have a RESTful WCF service and I’ve implemented an ErrorHandler such as the following:

public class MyErrorHandler : IErrorHandler, IServiceBehavior
{
    // OMITTED: IServiceBehavior Members

    public void ProvideFault(Exception error, MessageVersion version, ref Message fault)
    {
        DoSomeCustomLogging(error);
        WebOperationContext ctx = WebOperationContext.Current;
        ctx.OutgoingResponse.StatusCode = HttpStatusCode.InternalServerError;
    }           
}   

   
public class MyErrorHandlerElement : BehaviorExtensionElement
{
    protected override object CreateBehavior()
    {
        return new MyErrorHandler();
    }

    public override Type BehaviorType
    {
        get
        {
            return typeof(MyErrorHandler);
        }
    }
}
   

It’s hooked up in my web.config like so:

<system.serviceModel>
  <behaviors>
    <endpointBehaviors>
      <behavior name="Rest">
        <webHttp />
      </behavior>
    </endpointBehaviors>
  </behaviors>
  <extensions>
    <behaviorExtensions>
      <add name ="errorHandler" type="ACME.MyErrorHandlerElement, ACME.MyErrorHandler"/>
    </behaviorExtensions>
  </extensions>
  <serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
  <standardEndpoints>
    <webHttpEndpoint>
      <standardEndpoint name="" faultExceptionEnabled="false" helpEnabled="false"     automaticFormatSelectionEnabled="true"  />
    </webHttpEndpoint>
  </standardEndpoints>
</system.serviceModel>

For some reason, if my service throws an exception, 400 is returned to the client instead of 500. Any ideas why?

Answer 1

You need to modify the fault that gets passed in by reference, this isnt your regular webmethod call.

#Region "IErrorHandler Members"
Public Function HandleError(ByVal [error] As Exception) As Boolean Implements IErrorHandler.HandleError
  Console.WriteLine("HandleError called.")
  ' Returning true indicates you performed your behavior.
  Return True
End Function

' This is a trivial implementation that converts Exception to FaultException<GreetingFault>.
Public Sub ProvideFault(ByVal [error] As Exception, ByVal ver As MessageVersion, ByRef msg As Message) Implements IErrorHandler.ProvideFault
  Console.WriteLine("ProvideFault called. Converting Exception to GreetingFault....")
  Dim fe As New FaultException(Of GreetingFault)(New GreetingFault([error].Message))
  Dim fault As MessageFault = fe.CreateMessageFault()
  msg = Message.CreateMessage(ver, fault, "http://microsoft.wcf.documentation/ISampleService/SampleMethodGreetingFaultFault")
End Sub
#End Region

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