From ticket 844338

Please note I am using the "run to here option" on the last step of the project to perform maintenance. Also note that this does not always occur, I have attached a project I just had this error occur this morning on. I can run it fine several times, then suddenly I get the error. So you may need to run it several times as well to see the error.

I have been having consistent problems on playback on all of my scripts. The error seems to be at random, I have found no link to when or where it fails like this but it continues to happen at random points throughout my scripts.

The test log details are always the same however:

'7/29/2014 10:04:44 AM' - Error encountered during execution.
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'7/29/2014 10:04:44 AM' - Error inside the callback listener. Error: System.NullReferenceException: Object reference not set to an instance of an object.
   at ArtOfTest.WebAii.Design.DesignTimeExecution._runner_TestCompleted(Object sender, TestCompletedEventArgs e)
   at ArtOfTest.WebAii.Design.Execution.RunnerController.OnTestCompleted(ExecutionReturnValues result)
   at ArtOfTest.WebAii.Design.Execution.RunnerController.CallBackListener()
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'7/29/2014 10:04:44 AM' - Aborting....