It's not possible to login through GUI when disk is full

may be a message in that error report mentioning ctrl+alt+f1 and cleaning up some files to be able to log in again?

Yea that would be nice as a short-term workaround. As a proper solution however, I would suggest:

1. Rewriting the GUI login process so that it does not write any additional data to the disk.

 OR

2. Making sure that the relevant files are stored separately; so that regardless of how many mp3s the user downloads or regardless of how big /var/log messages and other log files grow they will never interfer with system functionality.

Generally, I would prefer the second solution because I bet that there is a ton of other important programs that will crash and/or fail abruptly with zero bytes free. The login process if of course one of the most important programs... since most users can't use their computer at all when they can't login.

Same problem with kubuntu 6.06 trying to login through KDM. Even worse, the user gets NO warning whatsoever - the KDM login screen just pops up again, with no indication of what went wrong.

bumping importance to high

I have removed duplicate on the general case of bug 22842, because I believe this programs (GDM, KDM) need special measure not touched by https://wiki.ubuntu.com/HandleNicelyLowDiskSpace?action=show
specification that I just began to wrote.

In fact I intend to separate kdm issue in it's own bug, as they are in fact two different problems, with both gdm and kdm needing to be patched.

Making it as affecting gdm (will fill a separate bug for kdm) rather than Ubuntu.

bug 62638 is related, but sufficiently different to not be considered a duplicate.

Why shouldn't bug 62638 be duped to bug 35217 ?

I think that #62638 is about /home being full, while #35217 is about / being full - probably these should be tackled separately.

This is not a duplicate. Rather 35217 does not seem to understand the problem where here it is understood. Perhaps, 35217 should be considered a duplicate of this thread. Clearly, this is an important problem that should be assigned to someone but it won't be with the attitude displayed on 25217. I would note that this issue occurs on Karmic most recent version. If you have encrypted files, then I do not believe there is a way to recover them but I am new and could be wrong about that. In 35217, the issue seems is also different because the proposed solution involves having the ability to login at the prompt which certainly isn't the case with this bug.