BuddyPress.org

I had the same problem, but I followed Davids advice and did this:

All plug-ins are disabled and I have a backup of my db too.

Went to phpmyadmin and in the table wp_sitemeta removed the values by clicking on the edit button from the 3 columns.

wpmu_sitewide_plugins

deactivated_sitewide_plugins

active_sitewide_plugins

Then went to cpanel>mysqldatabases and repaired the database

Then went into my file manager (my site always has issues with cache) and removed any of the long cache folders in wp_content/cache

Went back to my dashboard, left the plugins menu and went back into it and enabled buddypress. Then enabled all the other plugins.

Some the steps I’m sure aren’t needed but it worked for me.