I am still unable to get this issue fixed. I tried all the recommendations above, which are common sense and I still had no luck! Has anyone managed to fix the issue of not being able to see "Debug Error Info." instead of 500 Internal Server Error default by IIS 7? Thanks in advance!

I am using the above setup to pass the error to a custom 500 page, however my 404 goes to the custom 404 etc. Are you still having all errors sent to your 500 page?