Ubuntu 21.10 upgrade went without a glitch... except gnome

As usual the 21.10 upgrade caused the loss of all gnome-shell extensions, which in plain English means that ALL the customization of my desktop will have to be done all over again starting from scratch. Now I am stuck with a tweaks tool that does not have anything in the gnome-shell box and no extensions tab in the menu. Hovering with the mouse over the gnome-shell triangle (yes the one with the exclamation mark) informs me that the 'shell user-theme extension' is not enabled. Why I should have to enable the blessed thing together with a dozen extensions that worked fine as of yesterday... (and how I am supposed to do it)... is anybody's guess.

The upgrade took about 30 minutes and went without a glitch and now I have already wasted a couple of hours trying to figure out how to fix this broken desktop.

What am I supposed to do?

Found the solution in the ubuntu handbook: if you run into this same issue please read the entry titled: Gnome Tweaks 40 No Longer Manage Extensions, Use This Tool Instead. Tells you everything you need to do...

In a nutshell: one needs to fire up something called 'extensions': just open the application search box at the top of the screen by pressing <Super> and type e x t . . . and you should see and icon that looks like a green puzzle piece and take it from there.