I have an application that I inherited and I'm trying to make some updates to an existing module. It happens to be a custom login module.

I'm trying to integrate 2 factor authorization. The login itself works, but when I want to display the 2 factor fields after that, I get a 503 error on submission of the 2 factor code.

I tried to add an Application_Error event in global.asax, but that was never hit. I also tried to override the OnError event of the login control, but that is also never hit.

The OnInit is always hit during the post back that produces the 503, but not OnLoad. The strangest part is that if I step over each line of the OnInit, until I hit first thing outside of OnInit and then click Continue, everything works fine. If I just click Continue from the break point at the beginning of OnInit, it will fail with a 503 before getting to OnLoad, almost every time.

This points to some kind of asynchronous error but I can't imagine what it might be.

The login versus 2 factor fields are shown and hidden by Panel controls if that makes any difference.

The message that comes back with the error is "No sites currently exist for this installation."