Upgraded from 18.04 to 19.10, but "Activities" hangs system

Question

I upgraded to 19.10 but whenever I press the Super key or "Activities" button on the screen-top, the system becomes unusable. I can switch windows, but cannot do any work on, or close any application.

I saw this thread: Upgraded to 19.04 - System Freezing when Opening Activities Menu

but I am not sure how to remove the workspace grid which was given as the solution. Can someone suggest:

    1. If removing the workspace grid will solve the problem, or is there
       something else I need to run.
    2. How to remove the workspace grid.

thank you.

Answer 1

Completely disabling gnome extensions stopped the problem for me (not just disabling every extension; the extensions feature itself had to be switched off).

$ gnome-tweaks
Click "Extensions" in left sidebar
Turn the switch at the top right OFF
Log out & log in again (or reboot)

BTW, Alt-F2, restart can get out of the freeze once or twice.

Update 3/30/2020: There is something wrong with the remnants of old extensions, even if all extensions are disabled! Probably some gnome-shell bug or version-incompatibility corrupted things (just a guess). Anyway, I completely fixed the problem by doing

rm -rf $HOME/.local/share/gnome-shell 

while logged non-graphically on a vt (log out and wait for the login screen, then Ctl-Alt-F5 for a vt; Ctl-Alt-F1 to return to graphical login)

(I also removed .local/share/gnome-settings-daemon/ and session_migration-ubuntu but don't really know if that was necessary -- it's probably best to just remove .local/share/gnome-shell at first.)

Then log in graphically, re-enable gnome extensions using gnome-tweaks, and check if the problem is gone. If so, re-install any non-stock extensions from https://extensions.gnome.org/

P.S. FWIW, the "Dash to Dock" extension seemed to provoke problems, so I did not want to re-install it;, I tried "Workspaces thumbnails" instead and am happy with it.