First of all, thank you for taking great care of WPMU. While it looked intimidating to me way back WPMU 1.2 with the “run, don’t walk, to http://wordpress.com/” in the readme.txt, it continues to be a great adventure.
I experienced white screen in frontend and backend when I upgraded a development install way back to WPMU 2.9 beta 2 â€“ trunk-r2026 and ran http://mysite.com/wp-admin/upgrade.php script. Fortunately, I upgraded via FTP upload at that time and noticed wpmu-upgrade-site.php in wp-admin folder as I was uploading WPMU files and folders.
Running http://mysite.com/wp-admin/wpmu-upgrade-site.php gave me back my frontend and backend. Check in database showed new commentmeta table for all blogs. I am using WPMU latest trunk version now and no hiccups so far 🙂
Thank you again, Donncha.