I have been having this problem a while and tried all the different things suggested on the site and still have had no luck.
My problem is when I try and access the Gnome-Shell-Extensions part of Gnome-Tweak-Tool all I get is a blank screen.
This happens no matter which version of either program I use. My current version of Gnome-Tweak-Tool is 3.2-2, Gnome-Shell 220.127.116.11-0ubuntu1, Gnome-Shell-Common 18.104.22.168-0ubuntu1, and Gnome-Shell-Extensions-Common 3.2.0-2~webupd8-oneiric.
Does anyone have any other ideas of what I could try to get this working? Thanks for any help on this.