No longer supported, and they don't even have the decency to edit the page to tell us so.

Does not work at this time. "An error has occurred: Unsupported Content-Type: application/x-www-form-urlencoded" :(

The tiny W+bookmark icon logo appears at the right end of URL in the address bar (a lousy UI idea, but… maybe a necessary lesser-evil coding decision?) But once clicked, it fails with the error "An error has occurred: Unsupported Content-Type: application/x-www-form-urlencoded". Logged out and back in to Wikipedia, no change.

Maybe needs an update to work with current (v139.0.4) Firefox? Last updated 14 months ago. Disabled Ghostery, uBlock, etc. to no avail. Might test again after FF relaunch but still expecting failure given 14 of 34 reviews say "doesn't work".

straight up does not work

This doesn't work. First I had to search reviews to find out how to use it (button in search bar), but the button requests a log in to my account. When clicked, this goes to wikipedia website which I was already logged in to. Tried logging in and out, not working. What is the point of this?

Does not function the way it should.

This is way too basic. I would like to browse/manage/edit my reading lists from the app in the browser. All you can do is add articles to an "invisible" reading list and then find them in the app

There is literally no way to view your reading list or remove entries. All you can do is click the icon to add articles to the default list.
That isn't helpful at all! Why does this even exist? Just another Wikimedia Foundation project that nobody asked for.
Do they really expect users to add entries on PC and then open the app on your phone to view or delete entries?
You already implemented the sync feature, which is far more complicated. So, why don't you go all the way and add editing and viewing to the browser extension?

Doesn't work. Says I need to login, but the login button does nothing, so I can't.

Great idea if it actually worked. I get an error every single time. I'm logged in and nothing. Just non stop errors.

Great idea for an add-on, but it doesn't work. I have tried it on Linux, MacOS, and Windows, and had no success on any platform across three different machines.

I have high hopes for this add-on. However in the current version it only displays a "login" button redirecting me to the Wikipedia login page, whilst I am already logged-in on Wikipedia. Even a logout and then pressing this button doesn't makes this add-on recognizing that I am already logged-in.