therivits, I know what you mean…
(1) This problem occurred on my wife’s blog. On mine it upgraded flawlessly (even without deleting folders first).
(2) I did delete the folders, several times, after the issue started occuring. I deleted all folders/files, uploaded v2.5 and the same error that started this problem occurred. The app couldn’t find the Server(“PATH_INFO”) property and error’ed out on lines 72 and 75 of the wp-settings.php script. I deleted all folders/files again and uploaded v2.3.3 and that’s when I couldn’t get into my Admin account, though all my content was there. I even tried both methods (delete–>v2.5 and delete–>2.3.3) twice with the same results.
(3) The root cause, I believe, is that there’s a server configuration conflict with my host regarding the PATH_INFO variable. Subsequently, this cause the wp website to not load right, and then the database to not update right.
(4) Solution (yes, this was way too complicated): (a) I deleted all files and uploaded v2.3.3 since v2.5 was just not going to work. (b) I changed the database table prefix in the wp-config.php file from wp1 to wp2; this caused wp to reinstall again into new database tables. (c) Then, using the MySQL Admin tool, I dropped the wp2 tables (the ones just generated, except for wp2_users) and then renamed the wp1 tables with the wp2 prefix. I kepted the new wp2_users table with the new admin account data (I, of course, didn’t want to bring over any corrupt data from wp1_users).
This worked, essentially it created an entirely new website and database schema, but then overlayed the new db schema with the old tables/data except for the user table/data.
Nothing, else I tried worked. I did try updating the admin user’s password (user_pass) on the wp1_users table, but that didn’t work.
Anyways, my wife has her blog back with no data loss, just got to put some widgets back in (but those needed to be clean up anyway.
MySQL Admin tool:
http://www.mysql.com/products/tools/administrator/
