Always eager to avoid security risks hidden in older software, I first tried the new 3.0 version of the blog software WordPress on my local installation. I was impressed by the smoothness and speed of the upgrade process, which did not cause any hickups or even minor changes in the look of my handcrafted theme. So I upgraded the life site, too – without any problem.
That came only minutes later when I used the bulk upgrade for one plugin just out of curiosity (which always is a bad counselor): The blog went into maintenance mode but never came out again.
Lucky me that I was not the first person with this problem. One web search immediately yielded in the right recipe to correct this: Deleting the file .maintenance in the wordpress installation directory. And I was even more lucky to have a web presence with ssh-access, that made correcting this error a matter of seconds.
Fazit: WordPress 3.0 runs like a charm, but for the time being be careful with the bulk update for plugins.