The PAM appliance is being upgraded to 4.2.1, but it never came back online after the reboot. When the console was opened in VMware, the following errors were observed.
Booting 'PAM 4.2.1'
error: no such device: !uuid!.
Loading Linux ...
error: unknown filesystem.
Loading initial ramdisk ...
error: you need to load the kernel first.
Press any key to continue...
Failed to boot both default and fallback entries.
Press any key to continue..._
Privileged Access Manager 4.2.1
The /boot directory should have around 60 MB for the 4.2.1 upgrade, but in some instances, older files were left behind in /boot and resulted in insufficient space available in the directory.
Revert the PAM appliance to a pre-upgrade snapshot to restore functionality.
Prior to attempting the 4.2.1 upgrade again, perform /boot cleanup by downloading PAM_PRE_4.2.X_KERNEL_CLEANUP.p.zip from PAM Solutions & Patches and applying the bin file to the appliance.
For more information about the hotfix, please refer to the PAM_PRE_4.2.X_KERNEL_CLEANUP Hotfix documentation.