Comment 1 for bug 239958

You need to tell Bazaar your Launchpad username, like this:
    bzr launchpad-login flimm

There are two deeper bugs here:
    1. Neither Bazaar nor Launchpad tell you this.
    2. Bazaar gives you a stack trace -- it really shouldn't do that.

What version of Bazaar are you using? If you could paste the output of 'bzr version', that'd be really helpful.