The hackage 2 server should be able to log request details, and the response code etc, to a log file.
Another log file should contain extra details of any error responses returned.
This is not a Cabal bug.
@igfoo The description of this issue is a little vague, so I'm not sure if the features you're looking for have been implemented yet. If they are still lacking, please report this on the Hackage issue tracker.