User-defined Exception page is not displayed with SSL Forward Proxy on Exception for HTTPS URLs
If you have an SSL Forward Proxy on Exception rule configured (refer to the example below) and a user hits an exception upon accessing an HTTPS URL, no exception is displayed. This does not affect HTTP URLs.
ssl.forward_proxy(https, on_exception) ssl.forward_proxy.issuer_keyring(default)
Use the Builtin Exceptions