Update Manager get confused by captive portal

[Morten Welinder]

When starting Linux Mint 15 in a place with captive-portal wifi access, it gets
confused because the files it gets don't have the format (let alone contents)
that it expects.

That's not a big deal.

The big deal is that it seems unable to recover by itself. "Refresh" doesn't do
it. "sudo rm offending files" seems necessary.

I'm attaching one of the offending files.

[Roberto D'Auria (evfirerob)]

Same here, but with Linux Mint 16.

The files in /var/lib/apt/lists/ hold the HTML code of the captive portal web page instead of the data apt-get requires.
In my university other people have encountered this issue, and there is no way to fix it other than running a "rm -fr /var/lib/apt/lists/*" and then "apt-get update". Since there's no way to run it from the Update Manager, for a newbie it is difficult to discover how to fix that.

In addition, the package list gets corrupted *every time* the Update Manager updates it before the user has logged in on the captive portal.

This is rather annoying for me, and a real showstopper for a new Linux Mint user: the whole Update Manager becomes completely unusable whenever you connect to a network that requires a login.

Feel free to ask if you need any additional information.