mataiand

me too:
PHP Notice: Undefined index: comment_post_ID in /wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 1270
PHP Notice: Undefined index: delete_all2 in /wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 1300
PHP Notice: Undefined index: comment_post_ID in /wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 1270
PHP Notice: Undefined index: delete_all2 in /wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 1300

I’m getting this as well, however in different line:
PHP Notice: Trying to get property of non-object in /wp-content/plugins/jetpack/sync/class.jetpack-sync-module-posts.php on line 204

Thanks Bartosz,
turned out another plugin created some empty user roles.

that’s right, it works now. Some other plugin caused this problem.
Thanks for looking into this.

Some part doesn’t work correctly for me in multisite.
After I assign a given media item to a category, it gets correctly assigned, BUT the category count doesn’t get updated.
I tested this on a single site install and there it works perfectly with (both fresh install).