I was told earlier today that an old copy of Paint.NET wasn’t updating, along with the fact that the version was 2.63. This was a version that is pointed at the old Paint.NET website, http://www.eecs.wsu.edu/paint.net, for the update manifest, and that manifest has not changed since 3.0 was released. The problem is that the manifest was pointing at a copy of 3.0 that was sitting on my site, but I had long since deleted the file to make way for 3.01 through 3.08!
The file is back up and so older Paint.NET clients will now update just fine. It will offer you an update for 3.0, but will actually download and install 3.08. So if you know someone who was trying to update an old install of Paint.NET but it wasn’t working, then encourage them to try again!