[Forum] Upgraded from 3.8 to 4.1.9, forums work, but white screen for admincp

[GetGamer.com]

I've looked through the instructions on dealing with blank or white pages, but I'm unable to get the admin console to load after upgrading. The forums themselves work fine, it's the the admincp that is "blank."

EDIT: I'm able to load diagnostics.php and most pages directly, but not admincp/index.php

The site in question is www.bigblueball.com/forums/

Any suggestions?

[GetGamer.com]

Another oddity... when I run Suspect File Versions, it says "File does not contain expected contents" for ./index.php, but I just downloaded vBulletin today, and uploaded using ASCII transfer type. I've checked it and repeated, with the same results. Hmm... related?

[TheLastSuperman]

You disabled plugins (mods basically) before upgrading correct?

Here's a article, near the top it tells you how to quickly disable modifications via editing the config file - http://www.vbulletin.org/forum/showthread.php?t=259619 and in your case I believe it's a old outdated plugin causing your issue. If the problem ceases after you disable hooks globally in the config file then you can disable all mods in the product manager (then remove the added code in the config so they are enabled again but still off in the product manager due the fact you just disabled them manually) and start enabling them one by one (refresh the forum after you enable each new mod) and when the site "breaks" again you know exactly which mod was causing the issue .