As I mentioned on my previous post, I’m in the process of upgrading multiple WordPress blogs from WordPress 2.7.1 to WordPress 2.8. Typically, I’m able to just click on the bar that shows up at the top of the WordPress admin panel, but today, after upgrading 2 of the blogs, I noticed that the 3rd one that I got to did not have the upgrade bar available.

My guess is that the WordPress server tracks IP addresses to limit the amount of downloads, which makes sense, because before automatic upgrade, each user would download 1 zip file containing all necessary WordPress files, then once they had the file, those files would be uploaded to each and every server that they had a WordPress blog on, so all of the traffic and bandwidth usage would fall on the user and the hosting companies, not on the WordPress servers. But now, with the automatic upgrade option, each WordPress installation downloads the entire WordPress 2.8 zip file, unpacks it and installs it. That 1 file can’t be re-used between 5 different WordPress installations, causing the WordPress server to handle multiple downloads.

This is just a shot in the dark as to why the WordPress automatic upgrade option is available in some WordPress installations and not others, but if anybody has a definitive answer, please share it in the comments.