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c#sap-dotnet-connector

SAP Middleware Connector ArgumentException Collection was modified; enumeration operation may not execute

I'm developing an application which uses an SAP.Middleware.Connector from SAP AG (version 3.0.2).

This application executes an RFC in the background (using Task.Run) but after a few minutes, the app crashes:

ArgumentException caught in DefaultDomain: Collection was modified; enumeration operation may not execute .
Uncaught Exception in DefaultDomain

Unhandled Exception: System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
  at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
  at System.Collections.Generic.Dictionary'2.KeyCollection.Enumerator.MoveNext()
  at SAP.Middleware.Connector.RfcSessionManager.UpdateSessions(Object state)
  at System.Threading.TimerQueueTimer.CallCallbackInContext(Object state)
  at System.Threading.Executioncontext.RunInternal(ExecutionContext executionContext, ContextCallback, Object state, Boolean preserveSyncCtx)
  at System.Threading.Executioncontext.Run(ExecutionContext executionContext, ContextCallback, Object state, Boolean preserveSyncCtx)
  at System.Threading.TimerQueueTimer.CallCallback()
  at System.Threading.TimerQueueTimer.Fire()
  at System.Threading.TimerQueueTimer.FireNextTimers()
  at System.Threading.TimerQueueTimer.AppDomainTimerCallback()

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This is the code of the RFC execution:

return Task.Run(() =>
ConexionSAP cSap = new ConexionSAP();
cSap.ConectaSAP();
RfcDestination rfcDest = RfcDestinationManager.GetDestination(cSap.rfc);
            
RfcRepository rfcRep = rfcDest.Repository;
IRfcFunction function;
function = rfcRep.CreateFunction("XXXNAMEOFTHEFUNCTIONXXX");

//import parameters
RfcSessionManager.BeginContext(rfcDest);
function.Invoke(rfcDest);

//export parameters
RfcSessionManager.EndContext(rfcDest);
});

Please, can you help please with this?

Solution

  • Thank you for your help!

    I'm running on the answer of this. If you use BeginContext and EndContext on a Thread, the connector will try to renew the connection but now the thread containing the connection its gone causing the error, Collection was modified; enumeration operation may not execute.

    The solution was to delete the BeginContext and EndContext line, everything is fine and working.