Very strange
Did you ever use two factor authentication?
systemctl status mariadb (running?)
Try add a new admin user like this:
./adduser.php testuser password 10
in Chrome: right click->inspect->console (now login and see if any errors appear in this javascript console)
Try a different browser
Are you on the daily update or the monthly update?
(If daily, then there has only been 3 closed pull requests in the last 3 days. it seems unlikely that the last 3 would have caused an issue)
Fixed missing var declaration for description search in FDB tables
Device: Adding sensors to omnitron iconverter
Fix storing metrics for SMART
Could be worth checking recent package upgrades on your OS, did php update etc.
Also i take it this isn’t related to the Laravel upgrade from 1 month ago? New Requirements for 1.40 you applied php mbstring etc?