In a WPF application, the app simply crashes, without the above event being fired.

(I'm also registered to DispatcherUnhandeledException, which doesn't fire as well.)

I conclude that it doesn't fire since the handler is defined to place a log entry. When looking at the log, there's no corresponding entry.

It happens in a production environment; I'm unable to point at a particular scenario.

I've read few descriptions on scenarios where this might happen, but I still don't have a clear grasp on this. Can anyone share his experience / knowledge on this?

How can I find the root of the crash and solve it?

Many thanks.