Upgraded my blog to WordPress 2.6 yesterday and encountered an issue with permalinks not working anymore.
Apparently this is a wellknown issue, especially when you host your WordPress blog on Windows and use permalinks with the index.php in the link, then the permalinks may fail.
I found a few solutions to this, the first one was to change some of the php files and the second was to add some text into the Category base and tag base within the admin console. I went for the second solution, since it seemed must simple and adding the settings worked for me.
Here’s what I found of solutions on the issue:
2. Category base and Tag base solution (the simple one) 🙂
WordPress are working on it and the fix is included in the upcoming version 2.6.1.