Occasionally, the root account on ESXi can get locked out due to too many failed attempts at a login.
To reset the lockout follow the steps below;
At the console (either physically or via remote access software such as iLO on HPE machines press <F2> and log in as root, with the machine’s password.
Select “Troubleshooting Options”
Select “Disable ESXi Shell” and check its status chnages to ‘Enabled’
Prest ALT-<F1> to enter the ESXi shell, and enter username ‘root’ and password.
At the shell prompt, type;
pam_tally2 –u root –r
ALT-<F2> should now take you back to the normal ESXi interface.
Don’t forget to now disable the ESXi shell.
The account lockout should now have been reset.