I upgraded to 2.5.1 a week ago. I've been running WP for several years and upgrades are usually a snap, but after the upgrade this time I got a blank dashboard! Everything appears to be working fine, but the wp-admin/index page is blank.
Because I know the URLs for some admin areas I was able to access them by typing it in---everything works except: wp-admin/index.php and wp-admin/import.php
I deactivated my plugins before the upgrade. I did everything I was supposed to. I'm an old hand at upgrading; I've been running wordpress on this server for ages. I tried reuploading the files from a fresh download of the zip file and for one brief moment I got the Dashboard page, then I clicked away and it disappeared when I tried to access it again. :-( I have redone the upgrade several times now and I'm still not getting the admin/index page. :-(
The dashboard has showed up spontaneously twice and disappeared as soon as I clicked away. Counting all the attempts I've made I'd say I can access wp-admin/index.php about 2% of the time. :-(
I have also tried the upgrade with the default theme, with the old config file, with no plugins in the directory, I've tried resetting the permissions, I've deleted, reuploaded and upgraded more times than I can count. I'm NOT going to hack the code as suggested in this post: http://wordpress.org/support/topic/172650. I want an official fix. (I've got another site with WP and I'm not upgrading it until this bug is fixed.)
I do NOT want to rollback to the previous version: I LOVE wordpress and want to continue to upgrade.
There have been numerous post on this problem and no fixes. Is wordpress working on a fix?