@Amire80: What's confidential here (as this was filed as a security issue)?

If this is about yesterday specifically, I wonder if T143367: Users getting logged-out during minor network glitches could be related.
"I am having trouble signing in again" unfortunately does not tell us where, if removing cookies has helped, and if this only happened once or more often.

I'm not sure. The user mentioned the username publicly, so that's not a secret, but because it's about logging in, I wanted to be on the safe side. Feel free to change it to non-security or to merge it if it's a dupe.

This also happened to my account Amire80 at mediawiki.org yesterday and I had to refresh the page.

If you log into wikipedia.org, and then go to a different domain, its normal that you are not logged in on the first page view but only the second one (However, js is supposed to fake you being logged in initially)

I made bug public.

We would need way more information to diagnose:

• browser/OS
• exact steps (was logged in on wiki X, then went to wiki Y and wasn't) with exact time
• when reproducing the same steps in a private browsing windows, exactly what cookies are set (probably a HAR dump is the easiest) - this should be a private file/paste
• knowing when this started happening would also help

I asked the user at https://fr.wikipedia.org/wiki/Discussion_utilisateur:Elinruby#Log_in_bug .

I have not really been making note of the circumstances each time, and no, i have not tried clearing my cookies as the matter was not high on on my list of priorities. But the most often I see my username in the top right menu but when I post I get a blue bar above the textarea telling me that I am not signed in, and the submit button says submit anonymously. The post, if I proceed, picks up a machine address.

I have a global address and generally am automatically signed in to whatevever wiki I switch to. I'll take some notes and see if I can pin down a given browser. I use an english-language version of Opera and a French-language version of Mozilla,

Is the top right menu bar initially anonymous but immediately replaced by a logged-in bar, or is it logged in from the start? What happens if you refresh the page?

@Elinruby: Can you answer Tgr's questions please?