Not necessarily. Install this extension and you'll be able to use any unsupported extensions: https://addons.mozilla.org/en-US/firefox/addon/add-on-compatibilit

Not necessarily. Install this extension and you'll be able to use any unsupported extensions: https://addons.mozilla.org/en-US/firefox/addon/add-on-compatibility-reporter/ https://addons.mozilla.org/en-US/firefox/addon/add-on-compat... It'll also let you report their compatibility back to Mozilla and the extension developers so they know if the extension needs updating.