Part of my code was not running silently. I'm using the firebase SDK and think their helper functions are catching the exception without printing anything. Posting here to get feedback and also have somewhere on the internet this is being discussed. I'll write to firebase team as well. I attached the debugger and stepped through code until I found the line that is causing the issue. Commenting out the line will cause the program to run correctly. Upon inspection it turns out I have a null pointer exception in that line. The exceptions on background threads don't print to console. The problem here is that the exception, even though on main thread wasn't logging the error to console as it should. How do I know the code is running on the main thread? I print the Code (CSharp): Thread.CurrentThread.ManagedThreadId.ToString() before the faulty line and in Start() callbacks and make sure the id is the same. Here is the stack trace of the thread.