I started off with
sudo update-manager -dwhich told me there was a new release (in Beta) I proceeded and almost immediately got a python crash:
ImportError: No module named deprecationa bit of web searching gave me the solution and I downloaded and installed python-apt_0.7.94.2ubuntu3_amd64.deb. This took me once I restarted the upgrade, a little further until it stopped with the cryptic error:
E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.and told me that I might be trying to install a beta version (gosh!). This took me a little time to resolve, did a lot of searching around broken packages and removed a few which really ought to have long gone but a look at /var/log/dist-upgrade/main.log and the apt.log should have told me that the problem was the empathy package (an instant messenger) which claimed that there was a broken depends upon empathy-common (which I didn't have!) I removed empathy and it started downloading the new version of the operating system (all 2000+ packages!) this took some time but eventually prompted me to reboot. I rebooted and got to the screen where I select which operating system to run and the new version wasn't there! I tried the old version(which was still there and inevitably that crashed nastily as the only thing left of that was the Linux kernel! Fortunately I had installed other versions of Linux on the hard drive - if not I could have used a rescue disk - and from one of those edited the grub menu - which allows selection between them - to include the new version.
Reboot, select the Ubuntu Lucid and I got a black screen with a scary message about ureadahead having crashed and mountall being unable to connect to Plymouth (that's the graphical boot screen not a port in the south!). Booted back to a alternative working system to web search and after quite a few false trails looked at the /etc/fstab and spotted a line which I'd included to mount /proc/bus/usb which got Aladdin dongles working with the previous version of Ubuntu (as I no longer have the Aladdin dongle - used by my ex-work - I didn't need it). Then having edited that file (mounted the Ubuntu partition from the working OS) I rebooted, I still see that message about ureadahead but it quickly vanishes - so it was a red herring apart from telling me where in the boot process it was bombing out - and I could login to the upgraded Lucid Lynx system. Thanks to all at the bugjam for assistance. Now for testing of the running system!
There you are, wasn't that Lucid!
I meant to take some pictures of the day but, alas forgot!
Later Looks like the issue with grub was due to my having installed another version of Linux which, without asking, moved the MBR (master boot record) somewhere else where the Ubuntu system wasn't expecting it!