Service 500 error with ArgumentNullException

06-21-2009 3:57 AM |

I had a service working. I refactored the code to use MVVM. Unfortunately, I was testing all the code as I went so now I have a service that is broken. But only partially as one calls works just fine, but the other call fails before it gets to the first line of code (per the breakpoint).

The service itself wasn't touched, just the Silverlight app. The service is also in a seperate project from the Silverlight project and it's corresponding web project. I turned on IncludeExceptionDetailInFaults for the failing service and this is what I got:

"http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <s:Fault>
      <faultcode xmlns:a="http://schemas.microsoft.com/net/2005/12/windowscommunicationfoundation/dispatcher">a:InternalServiceFault</faultcode>
      "en-US">
        Value cannot be null.
        Parameter name: entity
      
        "http://schemas.datacontract.org/2004/07/System.ServiceModel" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
          <HelpLink i:nil="true"/>
          <InnerException i:nil="true"/>
            Value cannot be null.
            Parameter name: entity
          
            at System.Data.EntityUtil.ThrowArgumentNullException(String parameterName)
            at System.Data.Objects.DataClasses.EntityCollection`1.Add(TEntity entity)
            at ReadArrayOfVersePartialFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString , XmlDictionaryString , CollectionDataContract )
            at System.Runtime.Serialization.CollectionDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)
            at System.Runtime.Serialization.XmlObjectSerializerReadContext.ReadDataContractValue(DataContract dataContract, XmlReaderDelegator reader)
            at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, DataContract& dataContract)
            at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator xmlReader, Int32 id, RuntimeTypeHandle declaredTypeHandle, String name, String ns)
            at ReadCommentFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString[] , XmlDictionaryString[] )
            at System.Runtime.Serialization.ClassDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)
            at System.Runtime.Serialization.XmlObjectSerializerReadContext.ReadDataContractValue(DataContract dataContract, XmlReaderDelegator reader)
            at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, DataContract& dataContract)
            at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator xmlReader, Type declaredType, DataContract dataContract, String name, String ns)
            at System.Runtime.Serialization.DataContractSerializer.InternalReadObject(XmlReaderDelegator xmlReader, Boolean verifyObjectName)
            at System.Runtime.Serialization.XmlObjectSerializer.ReadObjectHandleExceptions(XmlReaderDelegator reader, Boolean verifyObjectName)
            at System.Runtime.Serialization.DataContractSerializer.ReadObject(XmlDictionaryReader reader, Boolean verifyObjectName)
            at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeParameterPart(XmlDictionaryReader reader, PartInfo part, Boolean isRequest)
            at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeParameter(XmlDictionaryReader reader, PartInfo part, Boolean isRequest)
            at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeParameters(XmlDictionaryReader reader, PartInfo[] parts, Object[] parameters, Boolean isRequest)
            at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeBody(XmlDictionaryReader reader, MessageVersion version, String action, MessageDescription messageDescription, Object[] parameters, Boolean isRequest)
            at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeBodyContents(Message message, Object[] parameters, Boolean isRequest)
            at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeRequest(Message message, Object[] parameters)
            at System.ServiceModel.Dispatcher.DispatchOperationRuntime.DeserializeInputs(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc& rpc)
            at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)
          System.ArgumentNullException
      
 I can't make sense out of what this means. Any ideas?