[deadmetheny]

Downvoting this is preposterous when it's a legit point. I've been using Firefox since the Phoenix days and now many of my old extensions that I've been using for years are non-functional; it's very much telling old users to pound sand for the sake of new users.

[scriptkiddy]

It's really not though. Try to put yourself in Mozilla's shoes for a moment:

You run arguably the most "free" and "open" internet browser in the business. You are constantly pushing for standardization in the face of competing browsers like Safari, Chrome, and Edge; all of which are trying to establish a walled garden powered by browser specific features. Your browser is consistently losing market share to Chrome because you don't have the cash to spend on marketing partnerships and pre-installs like Google does. Your browser is a means to an end, not the end itself. Your browser exists purely to push forward the tenets of the open internet and open source software. You need market share to push further standardization and improvements to the web experience. To get this market share you need to ensure that your browser offers at least the same performance and security as other browsers. In order to do this, you need to make some backwards incompatible changes or risk falling into obscurity. It's a sacrific you have no choice but to make.

[wtallis]

There's no question that breaking backwards compatibility is eventually necessary. That doesn't mean Mozilla did a good job of handling this transition. They absolutely screwed a lot of their existing users, and without good reason. They have had no overlap between support for WebExtensions and XUL extensions. They've been marking XUL extensions as "Legacy" for months but prohibiting you from installing a WebExtension on anything prior to FF 57, forcing everyone to deal with jarring changes to all of their extensions at the same time.

[SubiculumCode]

Backwards compatibility was not an option for Mozilla to move their architecture forward for a modern multi-core computer. A rational person would understand this and move on, or find a way to support a fork of FF 56. I have been a user of extensions since the earliest days of Mozilla Firefox (and earlier) and I love the new browser.

[wtallis]

The migration to a multiprocess architecture was handled relatively painlessly early this year. It had nothing to do with the migration to WebExtensions. Many extensions were incompatible with the multiprocess Firefox architecture, but when the user had one of those extensions enabled Firefox simply fell back to using a single process. Many popular and well-maintained extensions were modified to be multiprocess compatible without widespread user-visible breakage or loss of functionality.