uMatrix's repository has been archived and development has been discontinued:
https://github.com/uBlockOrigin/uMatrix-issues/issues/291
"Whoever is free to fork under a new name -- I may re-open and resume development in some future if ever I feel for it."
@fribbledom@mastodon.social How does this relate to uBlock Origin itself? I'm not informed on this subject, unfortunately.
@fribbledom 😌 phew, I thought he just ended development of everything. uBlock is still going.
@fribbledom Damn, that is the one I use, I think.
@fribbledom Noooooo 😢
@fribbledom Yeah, that is sad news. I've been enjoying that add on for years!
@fribbledom that suckath. I have been using and promoting uMatrix for years as an excellent replacement for NoScript
But developer time is not mine to command, so I say thanks to gorhill for the time he has put into this excellent project and thanks for having provided a safer web for me
@fribbledom Such a shame. It's my favourite add-on... Mane thanks to the developer, he did an amazing job.
Server run by the main developers of the project 
It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!
@fribbledom oh noooooooo