Upgrading Ubuntu 8.04 Desktop VM to 9.04

Short version: Don't try upgrading a 8.04 Ubuntu Desktop VM with only 4GB of disk to 8.10 - there isn't enough disk space.

I decided to start playing with Ubuntu 9.04 by upgrading a 8.04 Ubuntu Desktop VM I had. Since it was two version behind I followed the upgrade directions to bring it up to 8.10 first. A key bit in the directions is opening Software Sources and selecting "Normal releases" under the Updates tab, otherwise Update Manager won't show the update version.

I fired up the Update Manager, upgraded a number of packages, and then fired up the upgrade to 8.10. Unfortunately it died with the following message:

The upgrade aborts now. The upgrade needs a total of 649M free space on disk '/'. Please free at least an additional 243M of disk space on '/'. Empty your trash and remove temporary packages of former installations using 'sudo apt-get clean'.

So I did as it suggested and ran 'apt-get clean', which seemed to free up ~720MB of disk space:

# apt-get clean
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 3920768 2993528 729644 81% /
...

Now I trued Update Manager again, but it failed again with a similar message:

The upgrade aborts now. The upgrade needs a total of 975M free space on disk '/'. Please free at least an additional 306M of disk space on '/'. Empty your trash and remove temporary packages of former installations using 'sudo apt-get clean'.

So now I need 975MB of space. I give up.

Lesson learned, give Ubuntu more than 4GB if you think you might want to upgrade it.