Diligence and hard work pays off in the long run but procrastination pays off immediately.
One of the disadvantages of experience is that you retain memories of past failures. Like hunting with Dick Cheney and upgrading operating systems. A former Mandrake Linux fan, I once destroyed a fledging managed hosting business by insisting on installing the "latest" version on a number of servers.
When we collocated our primary web server in a fast data center in Denmark, we chose to install the then "latest" version of Ubuntu. It worked well, so well that except for security upgrades I elected not to upgrade to Gutsy. I repeated this decision when Gutsy was released and then again when Hardy came out. Then came Intrepid and in 4 more days Jaunty.
Ubuntu's support policy is to designate certain releases as "long term". These are supported for five years and the rest one. Feisty being one of the rest was moved from active repositories to "old" repositories. One could keep current for awhile by drawing from the old repositories and indeed, one of the tools used to upgrade had to be obtained in this way.
That tool is "do-dist-upgrade". It was written to upgrade from Feisty to Gutsy when both were in the active repositories and it expects to find the system to be upgraded to point to those repositories. But if you wait until Feisty is in the old repositories and Gutsy is still in the current repositories you have a problem.
Hundreds have stumbled on this problem and one guy - Alex Muntada - came up with an ingenious solution - https://bugs.launchpad.net/ubuntu/+source/update-manager/+bug/153980/com...
Open two sessions, start the upgrade pointing at the old repositories and at the precise moment when the upgrade wants to modify the repository sources, use the second session to point to the current archives.
Once upgraded to Gutsy, do-dist-upgrade functions as expected and you land in Hardy - 8.04.2. - a "Long Term Release". A good place to stop for now.