Problem mapping HttpHandler --> HTTP Error 404 Not Found

Question

I am having problems trying to map an HttpHandler in the web.config.

This is the relevant config bit:

Answer 1

It is also possible to experience this error if you have set up the handler for 32 bit, but you are running in 64 bit (or vice versa). It's easy to set up both and have all the bases covered.

Note "preCondition", and "scriptProcessor" differences.