Ok. Then I'll try to answer the question about the compatibility first of all with the example of extensions in Mypal 68 myself. Unfortunately, my answer has to be: No. Mypal 68.14.8b does not have a clear compatibility policy. Even some extensions that are actually FF68 compatible do not work for various reasons. One of them is the fact that Mypal 68 has never been a complete Firefox 68 version. Consider, for example, the still missing Internationalization & Localization feature I reported to Mypal's issues on GitHub three years ago that, however, some extensions, for example those dealing with time, date, timezones and so on, definitely require. uBlock Origin 1.62, on the other hand, works in Mypal 68.14.8b, although it is actually FF78+ compatible. Another example is the Scratchpad 0.7.1 extension. Since @feodor2 has removed the very useful, internal Scratchpad in Mypal 68.14.8b following Mozilla , I wanted to retrofit it with the help of this extension, which is FF72+ compatible. Unfortunately, that didn't work out. Not compatible. In Firefox 74, however, it works. So, Mypal 68.14.8b and extension compatibility is rather a game of trial and error. MinVersion numbers of extensions are only of limited use in this browser. At this point, I would personally appreciate a Mypal 68 browser with a state of development of 74 announced by its developer that then also should behave like its brother Firefox 74 in terms of compatibility. Strictly according to the motto: Whoever says A, must also say B. (German saying) And that's completely independent of whether I like these newer Firefox versions or not.