What would cause a RedirectionException in a Windows Workflow Service?

What exactly could be the root cause of the Workflow Service Host throwing the following type of RedirectionException:

System.ServiceModel.Channels.RedirectionException: The requested resource has moved to the one of the following locations:
    http://blah.mydomain.com/MyWorkflowService.svc
    at System.Runtime.AsyncResult.End[TAsyncResult](IAsyncResult result)
    at System.ServiceMo开发者_JAVA技巧del.Activities.Dispatcher.ControlOperationInvoker.InvokeEnd(Object instance, Object[]& outputs, IAsyncResult result)
    at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeEnd(MessageRpc& rpc)
    at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage7(MessageRpc& rpc)
    at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)

The documentation for RedirectionException is generic in terms of WCF and I get what it's for, but I'm not sure what condition is triggering the Workflow Service Host itself to throw it and there doesn't seem to be any documentation on it.

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I don't think I have ever seen this happen but according to Reflector it is the result of an InstanceLockedException being thrown which happens when a WF instance cannot be locked. This could either be because another WorkflowServiceHost has locked and loaded it or because of some inconsistency in the instance store database.