We are running 8.5.1 FP3 on W2003 X64. SSO with ActiveDirectory is enabled. Everything works OK. When a user is not in the ACL an HTTP 401 error occurs. (=correct)
Instead of this 401 we would like to redirect the user to another page on the same server.
SPNEGO authentication uses 401s as part of the authentication mechanism - look here for more info, specifically under ‘Conceptual Overview’ step #2. You could map a 401 error in domcfg.nsf, but I would tread lightly here, I don’t believe this has been tested against SPNEGO authentication.