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