Switched threads while processing a message for Contract '{0}' at Address '{1}'. UseSynchronizationContext property on ServiceBehaviorAttribute ...

Switched threads while processing a message for Contract '{0}' at Address '{1}'. UseSynchronizationContext property on ServiceBehaviorAttribute is set to true, and SynchronizationContext.Current was non-null when opening ServiceHost.  If your service seems to be not processing messages, consider setting UseSynchronizationContext to false.