In Umbraco 7.3.7 I'm having a problem where installing Merchello "looks" like it fails when the installer throws a YSOD with the following message:

 An unhandled exception occurred
 System.InvalidOperationException: The task runner has completed.
 at Umbraco.Web.Scheduling.BackgroundTaskRunner`1.Add(T task)
 at Umbraco.Web.Strategies.ServerRegistrationEventHandler.UmbracoModul    eRouteAttempt(Object sender, RoutableAttemptEventArgs e)
 at System.EventHandler`1.Invoke(Object sender, TEventArgs e)
 at Umbraco.Web.UmbracoModule.OnRouteAttempt(RoutableAttemptEventArgs args)
 at Umbraco.Web.UmbracoModule.ProcessRequest(HttpContextBase httpContext)
 at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
 at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

However, after a page refresh, the package (Merchello) has installed successfully.

I'm not sure if this is an Umbraco bug or something I need to handle due to a change in the process.

I did notice the Merchello section does not show up prior to the YSOD so I assume that the routing has to do with OnRouteAttempt has to do with Umbraco recognizing a new TreeController - but not at all sure?