I am running Windows 10 Pro version 1909 build 18363.959 For a few months now, I have occasionally been getting incorrect password but password is correct. If I keep on trying I can get the system to boot. This morning, I had the same problem but system just will not stop saying 'incorrect password'. Then I clicked on switch user, clicked on the same user (not switched) and I got it to accept the password and it booted but I could not open anything. After 5 or so minutes it started switching between blank screen and startbar every 2 or 3 seconds. Ctrl - Alt - Del > restart and it is working... Any ideas? Thanks in advance

Thanks Kapil for your suggestion. I decided to update to build 2004 and at least for the time being the fault seems to have disappeared.KapilArya

Incorrect password and booting issues | Microsoft Community Hub