Unfortunately it doesn't seem to work with the new Google page composition of expanded results to the right side of page.
There are no "Search by image" or "View Image" buttons and context menu "search by image" just opens Google Image search but does not search the image.

IF SEARCH IMAGE IN CONTEXT MENU DOESN'T WORK

ENABLE TAB PERMISSIONS FOR THE EXTENSION IN about:addons

View image in Google works! THANKS. Unfortunately Search by image in the context menu does not seem to work anymore on new Firefox versions.

I love this addon but the "view image" button is still not available in FF 101.0.1 (64-bit)

fonctionne à nouveau depuis début juin (v3.6.4)

Não funciona mais. Doesn't work anymore.

It doesnt work since May 28 2022

No longer works as of today, May 30, 2022.

As of 26/05/2022 this extensions is not working, here is a temporary workaround for those who might want it: https://github.com/bijij/ViewImage/issues/242#issuecomment-1139210812

Works when others have failed!

As of 4/26/22 working perfectly; like many 5 star add-ons it does something that should be done by default. I'm glad there are people out there who figure things like this out to save me thousands of dollars in therapy a year!