If you ever encounter trying to logon to the VCenter Appliance Management admin panel located at https://<your ip address>:5480 you may encounter an error that says “Unable to authenticate“. This can happen if your password expires, by default the VMware password will expire and will need to be changed prior to the expiration or via this method below, the policy to disable expiration can be set as long as you have access to the Admin Panel.
1. Shutdown the VCenter appliance
2. Take a snapshot of the VCenter Appliance before continuing, in case you need to revert backwards for whatever reason.
3. Power on the VCenter appliance while continually pressing the letter “e”
4. This will bring you to the GNU Grub Loader screen:
5. At this screen you will be able to move your cursor using the arrow keys to the end of the “consoleblank=0” section and add the following text “rw init=/bin/bash“. Notice the space between the 2 different sections.
6. Press F10 to continue booting.
7. At this command prompt you need to enter the command “passwd”
8. Type in your new password and than again as instructed.
10. Next type “umount /”
11. Once completed reboot the vCenter Server Appliance 6.5 by typing “reboot -f”
12. You will be able to logon to the VMware vSphere Appliacement Management using the new password you set.