''[Locked as a duplicate of https://support.mozilla.org/en-US/questions/1278754. Please follow up there, thanks.]'' I installed Nightly Firefox 74.0a1 and I am still able to sideload extension. But based on this article https://blog.mozilla.org/addons/2019/10/31/firefox-to-discontinue-sideloaded-extensions/, sideloading will not be supported in Firefox 74. I tested both of sideloading methods (https://extensionworkshop.com/documentation/publish/distribute-sideloading/?utm_source=blog.mozilla.org&utm_medium=post&utm_campaign=2019-sideloaded-discontinued) and the extension was able to be sideloaded successfully in both ways. Does anyone know the reason?