Each time you update an ESXi host, a copy of the ESXi image is saved on your host. If you think an ESXi upgrade might be making your host not work as expected in your environment, you can roll back the upgrade.

ESXi permits only one level of rollback. Only one previous build can be saved at a time. In effect, each ESXi 4.x host stores up to two builds, one boot build and one standby build.

When you manually boot into the standby build instead of the current boot build, an irreversible rollback occurs. The standby build becomes the new boot build and remains the boot build until you perform another update.


Reboot the ESXi 4.1 host.


When the page that displays the current boot build appears, press Shift+r to select the standby build.


Press Shift+y to confirm the selection and press Enter.

The previous upgrade rolls back. The standby build becomes the boot build.