TargetInvocationException on multiple WCF-service calls

Question

I'm using SL 4 and a .net-4 WCF service with a PollingDuplexHttpBinding. Calling the service and calling the client back from the service works fine. But as soon as I call the service, say 15 times without waiting for the async answer, I receive a TargetInvocationException after getting 0, 1 or 2 successful answers.

My attributes for the service are:

[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single,
    ConcurrencyMode = ConcurrencyMode.Multiple)]

This is in my web.config:

<behaviors>
  <serviceBehaviors>
    <behavior name="RecordProviderServiceBehavior">
      <serviceMetadata httpGetEnabled="true" />
      <serviceDebug includeExceptionDetailInFaults="false" />
      <dataContractSerializer maxItemsInObjectGraph="2147483647" />
      <serviceTimeouts transactionTimeout="05:05:00" />
      <serviceThrottling maxConcurrentCalls="500" maxConcurrentSessions="500"
       maxConcurrentInstances="2147483647" />
    </behavior>
    <behavior name="">
      <serviceMetadata httpGetEnabled="true" />
      <serviceDebug includeExceptionDetailInFaults="false" />
    </behavior>
  </serviceBehaviors>
</behaviors>
<serviceHostingEnvironment multipleSiteBindingsEnabled="true"/>
<bindings>
  <pollingDuplexHttpBinding>
    <binding name="multipleMessagesPerPollPollingDuplexHttpBinding"
       maxBufferSize="2147483647" maxBufferPoolSize="2147483647" maxReceivedMessageSize="2147483647"
       maxOutputDelay="00:00:00.200" duplexMode="MultipleMessagesPerPoll" />
  </pollingDuplexHttpBinding>
</bindings>

And like this, I instantiate the service on client side:

var binding = new PollingDuplexHttpBinding(PollingDuplexMode.MultipleMessagesPerPoll)
                          {
                              MaxBufferSize = 2147483647,
                              MaxReceivedMessageSize = 2147483647
                          };
        _service = new ServiceClient(new InstanceContext(this),
                                            binding,
                                            new EndpointAddress("path to .svc"));

As I'm new to WCF: did I miss something?

Answer 1

TargetInvocationException should have a InnerException property containing the actual exception, it might give you some clues.