title: The agent is stopped or has been stopped, no additional provocateurs can be created
body: <p>Every once in a while, I start to see the following exception. I'm not sure how to fix it, or why does the app think it's stopping. The only way to fix it is to restart the app. What is the best practice for this error? What is the reason for this error?</p>
  
  <pre><code>System.OperationCanceledException: The agent is stopped or has been stopped, no additional provocateurs can be created.
  at GreenPipes.Caching.Internals.NodeValueFactory`1.&lt;CreateValue&gt;d__7.MoveNext()
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at offset 12
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(System.Threading.Tasks.Task task) at offset 38
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(System.Threading.Tasks.Task task) at offset 46
  at GreenPipes.Caching.Internals.NodeTracker`1.&lt;AddNode&gt;d__38.MoveNext()
  </code></pre>