WordPress 2.6 IIS Permalink Bug
Some of my readers have noticed alot of broken links on my blog latley. I recently upgraded to WordPress 2.6 on my IIS server and it seems that there was a known bug that was not fixed by the WordPress team before the final version of WordPress 2.6 was rolled out.
Note: IIS users without .htaccess must use /index.php/ in there permalink structure.
I did check my site after the upgrade and everything seemed fine. However, I am pretty sure I didn’t clear my browsers cache 1st. Hence I was completely unaware of the issue, until I noticed a severe drop in traffic and emails started pouring in.
404 error appears on all permalinks when blog uses following permalink structure: /index.php/%postname%/.
Front page with posts shows OK. Clicking any post headings will give 404 error. Also archives (myblog.com/index.php/2008/07/) will give 404 error.
Pages (myblog.com/index.php/page title/) are working OK.
Tried with different themes and they all produce same error. Changing permalink scheme to default will solve problem but that’s not an option normally.
Here is the semi-workaround / hack / someone REALLY should have fixed this properly fix:
If you need/want the index.php to be there, then on the Settings->Permalinks screen, add some values in for the category and tag bases. The words “category” and “tag” will do just fine. As long as they are not blank, this should work around the bug.
Note: This Bug is scheduled to be fixed in WordPress Release 2.6.1
If you would like to read the other server OS fixes click here.
If you would like to read the whole support thread click here.

Umesh | September 1st, 2008 at 5:26 am
Thanks…you made my day…I was facing the same problem and now everything is fine.
Umesh