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.NET 4.0 WCF service throws AddressAlreadyInUseException when moved to .NET 4.5

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This article helps you resolve the exception AddressAlreadyInUseException that occurs when .NET 4.0 Windows Communication Foundation (WCF) service is moved to .NET 4.5.

Original product version:   Windows Communication Foundation
Original KB number:   2773443

Symptoms

Consider the following scenario:

You have a .NET 4.0 WCF service configured with a NetTcpBinding and an endpoint sharing a single port and explicitly configuring listenBacklog or maxConnections on the netTcpBinding to the default values of 10. An example of this configuration is as follows:

<system.serviceModel>
   <services>
      <service name="MyAssembly.MyNamespace.MyService" behaviorConfiguration="MEX">
         <endpoint address="net.tcp://localhost:56543/MyService"
            binding="netTcpBinding" contract="MyAssembly.MyNamespace.MyServiceInterface"
            bindingConfiguration="NetTcpBindingConfiguration" />
         <endpoint address="net.tcp://localhost:56543/MEX" 
            binding="mexTcpBinding" contract="IMetadataExchange" />
      </service>
   </services>
   <bindings>
      <netTcpBinding>
         <binding name="NetTcpBindingConfiguration" listenBacklog="10" maxConnections="10" >
         </binding>
      </netTcpBinding>
   </bindings>
   <behaviors>
      <serviceBehaviors>
         <behavior name="MEX">
            <serviceMetadata/>
         </behavior>
      </serviceBehaviors>
   </behaviors>
</system.serviceModel>

In this scenario, you may receive an AddressAlreadyInUseException when the application is moved to .NET 4.5. The exception is similar to the following:

System.ServiceModel.AddressAlreadyInUseException: There is already a listener on IP endpoint 0.0.0.0:xxxx. This could happen if there is another application already listening on this endpoint or if you have multiple service endpoints in your service host with the same IP endpoint but with incompatible binding configurations. ---> System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress) at System.Net.Sockets.Socket.Bind(EndPoint localEP) at System.ServiceModel.Channels.SocketConnectionListener.Listen() --- End of inner exception stack trace --- at System.ServiceModel.Channels.SocketConnectionListener.Listen() at System.ServiceModel.Channels.BufferedConnectionListener.Listen() at System.ServiceModel.Channels.ExclusiveTcpTransportManager.OnOpen() at System.ServiceModel.Channels.TransportManager.Open(TransportChannelListener channelListener) at System.ServiceModel.Channels.TransportManagerContainer.Open(SelectTransportManagersCallback selectTransportManagerCallback) at System.ServiceModel.Channels.TransportChannelListener.OnOpen(TimeSpan timeout) at System.ServiceModel.Channels.ConnectionOrientedTransportChannelListener.OnOpen(TimeSpan timeout) at System.ServiceModel.Channels.TcpChannelListener`2.OnOpen(TimeSpan timeout) at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout) at System.ServiceModel.Dispatcher.ChannelDispatcher.OnOpen(TimeSpan timeout) at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout) at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout) at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)

Cause

WCF does not support service endpoint with NetTcpBinding and mex endpoint with mexTcpBinding be on the same port yet having differently configured listenBacklog and maxConnections. If you configured your 4.0 service to have the listenBacklog and/or maxConnections to be 10, it worked because these defaults were the same for both NetTcp and mexTcpBinding. However in 4.5 to simplify the quotas, these were increased to be a multiple of the processor count (12 * processor count) unless explicitly configured. Therefore when this 4.0 service is moved to 4.5 framework, the defaults change implicitly to the new values for the endpoint where they were not explicitly configured leading to a mismatch with these values for the endpoint where they are explicitly configured causing the AddressAlreadyInUseException.

Resolution

To resolve this issue, apply one of the updates that are described in the following Knowledge Base (KB) articles:

Note

For more information about this issue, see Issue 2 in the WCF section.

Workaround

To work around this issue, choose one of the following options:

  1. Remove the explicit configuration for listenBacklog and maxConnections and restart the service.

  2. Host the service endpoint with netTcpBinding and mex endpoint with mexTcpBinding on different ports.

More information

For more information on hosting the service endpoint with netTcpBinding and mex endpoint with mexTcpBinding on different ports, see WCF Troubleshooting Quickstart.