Hi albert43, there is a problem with an expired certificate. The Add-ons team is scrambling to update various Mozilla products; I don't know what is going on with Tor. I think the Tor browser is built using the Extended Support Release of Firefox 60, and therefore there is a setting to turn off signature verification for extensions. This obviously is not as safe, but might be the best compromise in the short run until the Tor team announces their version of the fix. (1) In a new tab, type or paste '''about:config''' in the address bar and submit that. Click the button promising to be careful or accepting the risk if presented. (2) In the search box above the list, type or paste '''xpin''' and pause while the list is filtered (3) Double-click the '''xpinstall.signatures.required''' preference to switch it from true to false Unfortunately, this creates the potential for a bad actor to serve Firefox an unsigned update, so it's definitely not a long-term fix. You can turn off extension auto-updating as a mitigation: (4) In the search box above the list, type or paste '''autoup''' and pause while the list is filtered (5) Double-click the '''extensions.update.autoUpdateDefault''' preference to switch it from true to false With that change, the Add-ons page will show a new "Updates Available" section in the left column when updates are detected so you can examine them individually before updating.