I don't think CGI::Application plays well with fatalsToBrowser.

I have to apologize, to CountZero too - I was totally wrong on this - fatalsToBrowser works fine - I've been having my mix of mod_perl and CGI configured wrong - as I discovered now after looking into this, but now fixed it. fatalsToBrowser works fine with mod_perl with nothing else required.. must be CGI::Application causing the problem in the OP's question. Downvote me severely.