Upgraded to 2.6 from 2.2.X. Had a custom template I was using for the site, but it defaulted to the default template after the successful upgrade.
I modified my CSS file to have the comment in the header per here:
http://codex.wordpress.org/Theme_Development
However, while I can see the custom template, I cannot switch to it. The preview window loads with the progress bar, but never finishes loading. I can preview it in default or classic and switch to either one, but my custom template never loads.
I'm at a complete loss as to what the problem is. Does anyone have any suggestions?
UPDATE: Also, I think I can safely say it's not the CSS file. I tried copying and pasting the classic style.css file into the custom theme, and it still wouldn't work.