Close FirefoxPress [Windows Key]+[R] → Type in %APPDATA% > click OKPOpen C:\Users\*USERNAMEGOESHERE*\AppData\Roaming\Mozilla\Firefox\Profiles\ Open your <profile>.default directoryOpen the file extensions.json with <text editor>Replace all instances of “appDisabled”: true with “appDisabled”: falseReplace all instances of “signedState”:-1 to “signedState”:2Save and start browserDisable and re-enable all extensions in about:addons