一応手順
Go to about:support in the URL bar.
Open your profile directory.
Open extensions.json in your preferred editor.
Replace all "appDisabled":true with "appDisabled":false.
Replace all "signedState":-1 with "signedState":2.
Save the file.
Restart Firefox.
Go to about:addons in the URL bar.
Disable then enable each addon to get it working again.

最後わかりにくかったけど、無効にしてまた有効それで起動すれば直る