[daniel1212]

I have not updated, but I just search https://duckduckgo.com/?q=This+extension+could+not+be+verified+for+use+in+Firefox+and+has+been+disabled.&t=newext&atb=v447-1&ia=web and: https://www.thewindowsclub.com/allow-unsigned-extensions-installed-firefox Type about:config into the URL bar in Firefox

In the Search box type xpinstall.signatures.required

Double-click the preference, or right-click and selected “Toggle”, to set it to False.

Lets us know if this works for you.

[KevinB]

In the Search box type xpinstall.signatures.required. Double-click the preference, or right-click and selected “Toggle”, to set it to False.

I thought I'd follow up on this post. I went through that process yesterday and setting that to false had no impact.