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\r\n   at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)\r\n   at Microsoft.Rtc.Internal.Sip.TcpTransport.OnReceived(Object arg)\r\n   --- End of inner exception stack trace ---\r\n   --- End of inner exception stack trace ---\r\n   at Microsoft.Rtc.Signaling.SipAsyncResult`1.ThrowIfFailed()\r\n   at Microsoft.Rtc.Signaling.Helper.EndAsyncOperation[T](Object owner, IAsyncResult result)\r\n   at Microsoft.Rtc.Internal.UCWeb.UCWAuthenticatedEndpoint.OotyUserEndpointEstablish_callback(IAsyncResult asyncResult)\r\n   --- End of inner exception stack trace ---\r\n   at Microsoft.Rtc.Internal.UCWeb.Utilities.AsyncHelper.EndAsyncCall[T](IAsyncResult asyncResult, String methodName, T ucwScopeInstance)\r\n   at Microsoft.Rtc.Internal.UCWeb.UCWAuthenticatedEndpoint.EndSignIn(IAsyncResult asyncResult)\r\n   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 host name must be the common name (CN) of the SSL certificate used securing OWA communication.

Example for a non working IM configuration

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

Example for a working IM configuration

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




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