This post was originally published here

Following my last post and continuing on the pain points of BizTalk Server infrastructure tasks migration, I end up founding another interesting error: WCF-Custom Reason: System.ArgumentException: An item with the same key has already been added.

Again, we indeed did more than a simple migration, we take this opportunity to improve our solutions and/or BizTalk Server environment to update our applications to the new the new available features. In terms of WCF-SAP Adapter, we are no longer using traditional RFC and we will be starting using SAP .NET Connector (NCo). Despite WCF-SAP adapter will continue to support both the RFC SDK and the SAP .NET Connector, SAP has announced deprecation of its classic RFC SDK (no longer be supported after March 31, 2016) and because of that, it should be used anymore.

While trying to connect our BizTalk Server Receive Location to SAP in order to listen to incoming messages, we initially got this error message:

The Messaging Engine failed to add a receive location “WcfReceiveLocation_SAPBinding_IdocDELVRY05V3R700_Custom” with URL “sap://CLIENT=400;LANG=EN;@a/SERVERNAME/00?ListenerGwServ=sapgw00&ListenerGwHost=LISTENERHOST&ListenerProgramId=BTS_LIST&RfcSdkTrace=False&AbapDebug=False ” to the adapter “WCF-Custom”. Reason: “System.ArgumentException: An item with the same key has already been added.

at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)

at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)

at Microsoft.Adapters.SAP.NCo.RfcServerConnection.Open(RfcClientConnection conn)

at Microsoft.Adapters.SAP.SAPInboundContract.InitializeRfcServerConnectionNCo(String connectionArguments)

at Microsoft.Adapters.SAP.SAPInboundContract.StartListener(String[] listenerActions, TimeSpan timeout)

at Microsoft.ServiceModel.Channels.Common.Channels.AdapterChannelListener`1.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)

at Microsoft.BizTalk.Adapter.Wcf.Runtime.WcfReceiveEndpoint.Enable()

at Microsoft.BizTalk.Adapter.Wcf.Runtime.WcfReceiveEndpoint..ctor(BizTalkEndpointContext endpointContext, IBTTransportProxy transportProxy, ControlledTermination control)

at Microsoft.BizTalk.Adapter.Wcf.Runtime.WcfReceiver`2.AddReceiveEndpoint(String url, IPropertyBag adapterConfig, IPropertyBag bizTalkConfig)”.

BizTalk Server WCF-SAP Adapter: System.ArgumentException: An item with the same key has already been added


What I found out was that this error was somehow related to the error reported in my previous post: BizTalk Server WCF-SAP Adapter: SAP.Middleware.Connector.RfcCommunicationException: LOCATION CPIC (TCP/IP) on local host BTSSERVERNAME with Unicode, ERROR service ‘?’ unknown.

The reason why I’m saying that is that each time I restarted the BizTalk Server Host Instances, the error that I got the first time I try to enable the port was this service ‘?’ unknown error. Afterward, whenever I tried to enable this port, I would receive this new error:

  • System.ArgumentException: An item with the same key has already been added

Why this is happening for me is a mix of a small bug and consistency, let me explain better:

  • Why consistency? This because in fact, you cannot have two SAP Receive Locations listening to the same SAP endpoint/SAP Listener Program Id.
    • Actually, this should be when this error would normally occur.
  • Why a small bug? Because in fact there isn’t any Receive location enable for that specific SAP endpoint/SAP Listener Program Id. What is happening is that despite the error and the receive location became automatically disable it somehow stores in memory that SAP endpoint/SAP Listener Program Id


The solution is very simple and stupid:

  • Restart the host instance that is running that Receive Location

After that, this problem goes away, but make sure you solve all the problems, or this may happen again.

Author: Sandro Pereira

Sandro Pereira lives in Portugal and works as a consultant at DevScope. In the past years, he has been working on implementing Integration scenarios both on-premises and cloud for various clients, each with different scenarios from a technical point of view, size, and criticality, using Microsoft Azure, Microsoft BizTalk Server and different technologies like AS2, EDI, RosettaNet, SAP, TIBCO etc. He is a regular blogger, international speaker, and technical reviewer of several BizTalk books all focused on Integration. He is also the author of the book “BizTalk Mapping Patterns & Best Practices”. He has been awarded MVP since 2011 for his contributions to the integration community.