I clicked "log out" accidentally and wanted to interrupt it. The page Special:UserLogout wasn't finished loading in my browser, but I was still logged out. Now every time I try to log in I get logged out immediately (servers are sending header to delete cookies). This issue persists in different browsers (I've tried Firefox, Chrome), but I don't have the same problem if I try another account. Account having problem is Drundia.
Cookies are ordered to be deleted by one of several requests:
https://en.wikipedia.org/wiki/Special:CentralLogin/complete?token=*** (it displays error "No active login attempt is in progress for your session.")
https://en.wikipedia.org/wiki/Main_Page (or another normal WP page, in this case the page itself displays me as anon)
https://login.wikimedia.org/wiki/Special:CentralAutoLogin/refreshCookies?type=1x1&wikiid=enwiki&proto=https
https://login.wikimedia.org/wiki/Special:CentralAutoLogin/checkLoggedIn?wikiid=metawiki&proto=https&type=1x1&from=enwiki
Response headers involved:
x-centralauth-status: Not logged in
Set-Cookie: loginwikiSession=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0; path=/; secure; httponly
loginwikiUserID=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0; path=/; secure; httponly
forceHTTPS=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0; path=/; httponly
centralauth_User=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0; path=/; secure; httponly
centralauth_Session=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0; path=/; secure; httponly
I can assume that during my logout some background task to wipe my auth tokens was started, but it wasn't properly stopped as it should have been (because of user abort?).