[ Thanks to Ramsai
for this link. ]
“Preparation
“When upgrading your system from one release to the next, there
are certain requirements that you must meet in order to be
successful. First of all, and most importantly in this instance,
this upgrade path is only possible from Ubuntu 9.04 “Jaunty
Jackalope” to Ubuntu 9.10 “Karmic Koala”. If you are using a
release previous to 9.04 (8.10 or earlier), stop now. This upgrade
process will not work, is not supported and will likely cause
problems. If you are unsure which version you have installed, you
can run this command in your terminal to find out. (Applications
> Accessories > Terminal)“lsb_release -a
“If you find that you are on a release previous to Ubuntu 9.04,
you will need to decide whether it is best to do a fresh
installation or do an incremental upgrade leading up to 9.10.
Incremental upgrades, as well as fresh installations are beyond the
scope of this article, but there is detailed documentation on the
matter found here:”