YouTube made some minor UI changes, which caused the current version of Return YouTube Dislike in the Mozilla Addons Store to not work. A fix has been submitted for review to Firefox and other browser stores, but that takes time and Mozilla has get to accept the new version. Adding the current version manually from their GitHub page does work just fine, if you don’t feel like waiting.
YouTube made some minor UI changes, which caused the current version of Return YouTube Dislike in the Mozilla Addons Store to not work. A fix has been submitted for review to Firefox and other browser stores, but that takes time and Mozilla has get to accept the new version. Adding the current version manually from their GitHub page does work just fine, if you don’t feel like waiting.
https://github.com/Anarios/return-youtube-dislike/issues/944