Ubuntu Lucid 10.04 LTS and I just aren't getting along well so far. In past Linux upgrades I was able to keep my data and config files (after checking config files against new versions for any major changes), and the upgraded system and applications behaved the same way. This hasn't been the case for my Lucid LTS upgrade.
I have mod_fcgid for my PHP sites, and after my Lucid upgrade I noticed that PHP uploads such as images, photos and documents were being corrupted quite frequently, and it was happening on both Wordpress and Simple Machines Forum (SMF). I spent a lot of time troubleshooting it to no avail. I was about to give up and either roll back to Hardy LTS or put PHP on Windows and run my sites there when I stumbled across this bug report: Uploads greater than 64 kilobytes corrupted when using Apache mod_fcgid
Lucid LTS's mod_fcgid has this bug, and to automatically get the patch you have to have security.ubuntu.com in your /etc/apt/sources.list, for example:
deb http://security.ubuntu.com/ubuntu lucid-security universe
Then run updates and upgrades.
I suppose it's partially my fault for not having security there in the first place, but I thought the security patches would eventually show up on the distribution mirrors. Apparently not yet. And also this seems more like a bug fix than a security issue.