The smart proxy can return 400 bad request HTTP responses for a large number of configuration problems, which are all logged in the smart proxy's proxy.log file. The Foreman UI though only reports the 400 bad request error, but doesn't indicate that this originated from a call to a smart proxy, or which proxy it was.

The UI should be improved to indicate the origin of the HTTP error and preferably a hint to look in the proxy's log files. If possible (and if it doesn't expose confidential data) then the proxy could return a more meaningful error in the body of the HTTP error to be displayed.