access denied for fast cgi URI

Trying to add a fast cgi application and getting "access denied" and 403 error when URI is accessed.
I registered my fast cgi app under external app. filled all requisite parameters.
I added a context type fast cgi and added URI and selected the external app.
I started the app in the background and it is listening on port. when i try to access the URI from browser i get a 403 error and in the error i find .
Context [/webhook] is not accessible: access denied.
I am following the code and am still clueless what t is going on.
Please advise.