I was able to solve it in a “surgical” way.
Here’s what I’ve done:
Note: I had backed up all the file (using FTP) to a local folder before upgrading, so I knew I can always re-upload ver 3.5 back (but wanted to avoid it)
The elimination process:
1. Access FTP
2. Change each plugin’s folder name (under /wp-content/plugins) to something like “akismet – x” (w/o the “).
3. After each folder name-change try to re-access admin panel.
4. Once able to access the admin panel I knew which plugin was causing this and have deleted that plugin from the Plugins page.
5. I kept testing the admin panel to make sure I have a fully functional WP as I saw there’s more than one plugin causing some functionality issues; after I accessed the admin panel I was not able to add a new page or edit a page for example.
Now it is all back and running okay.
~30 mins spent on the process!
