in reply to Net::XMPP registering account from client
I've never used Net::XMPP before, so I may be out in left field, but I'd guess by the error message that when your auth failed, the server disconnected the connection. (That sort of error message often implies that an internal value in the object is undef, such as the connection handle.) Because of that, it might simply be that you need to do another Connect before trying to register.
I'm sorry in advance if I'm off-base.
When your only tool is a hammer, all problems look like your thumb.