OWA IM TlsFailure with Skype for Business

Exchange Server 2013 Exchange Server 2016Problem

When you integrate Skype for Business Server instant messaging with Exchange Server 2013 or Exchange Server 2016, you might encounter the following error in the OWA InstantMessaging log files.

ERROR:UCWEB Failure: Code=TlsFailure, SubCode=TlsRemoteDisconnected, Reason=\r\nMicrosoft.Rtc.Internal.UCWeb.Utilities.UCWException: Unknown error (0x80131500) 
---> Microsoft.Rtc.Signaling.TlsFailureException: Unknown error (0x80131500) 
---> Microsoft.Rtc.Internal.Sip.RemoteDisconnectedException: Peer disconnected while outbound capabilities negotiation was in progress 
---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host   
at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)   
at Microsoft.Rtc.Internal.Sip.TcpTransport.OnReceived(Object arg)   
--- End of inner exception stack trace ---
--- End of inner exception stack trace ---
at Microsoft.Rtc.Signaling.SipAsyncResult`1.ThrowIfFailed() 
at Microsoft.Rtc.Signaling.Helper.EndAsyncOperation[T](Object owner, IAsyncResult result)
at Microsoft.Rtc.Internal.UCWeb.UCWAuthenticatedEndpoint.OotyUserEndpointEstablish_callback(IAsyncResult asyncResult) 
--- End of inner exception stack trace --- 
at Microsoft.Rtc.Internal.UCWeb.Utilities.AsyncHelper.EndAsyncCall[T](IAsyncResult asyncResult, String methodName, T ucwScopeInstance)  
at Microsoft.Rtc.Internal.UCWeb.UCWAuthenticatedEndpoint.EndSignIn(IAsyncResult asyncResult)   
at Microsoft.Exchange.Clients.Owa2.Server.Core.InstantMessageOCSProvider.<>c__DisplayClass33.b__32(RequestDetailsLogger logger)

The log files are located at

\Program Files\Microsoft\Exchange Server\V15\Logging\OWA\InstantMessaging


The Exchange Server OWA hostname must be the common name (CN) of the SSL certificate for securing OWA communication.

Example of a non-working IM configuration

  • OWA host name: owa.varunagroup.de
  • SSL certificate CN: mobile.varunagroup.de

Example of a working IM configuration

  • OWA host name: owa.varunagroup.de
  • SSL certificate CN: owa.varunagroup.de


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