Authentication error

Hi ~everyone
I have a problem and need help

UltraVNC> :5902> Enter the normal lock screen> However, the password field will always refresh.
I key in a letter or press a key to keep it typing, and it will be cleared immediately. There is an Authentication error message below the field. (Left picture)?
If I press ESC, it returns to the initial blank screen (right picture). Move the mouse a little, and it goes here to enter the password but authentication error screen (picture on the right).
If I open vsphere first, after starting VM Remote Console from there, I open the UltraVNC connection again, the password will not refresh. But not every time.

Can anyone help me out, thank you.

Are you able to boot the host to Run Level 3 (no GUI) and login at a console? How about SSH?