작성: Oleksandr (개발자), 날짜: 9월 27, 2017 · 고유 주소

Unfortunately, WebExtensions (the new API for Firefox 57+) does not have the functionality for the correct operation of this addon in Firefox.
So this addon will no longer work with the release of Firefox 57 in November 2017!
This is the inevitable change in Firefox - all Xul-addons will die out in Firefox 57
https://blog.mozilla.org/addons/2017/02/16/the-road-to-firefox-57-compatibility-milestones/

But you can install Firefox 52 ESR and enjoy work until June 2018
https://www.mozilla.org/en-US/firefox/organizations/faq/