Guest OS stuck at GRUB screen after reverting Virtual Machine snapshot

Products

• VMware vSphere ESXi 8.0

Issue/Introduction

Virtual Machines may fail to boot and remain stuck at the GRUB screen immediately following a snapshot restoration. This behavior typically occurs under the following conditions:

• A snapshot revert is performed after a failed Operating System (OS) update.
• The VM powers on successfully in EFI or BIOS mode.
• ESXi indicates that disks are correctly attached, but the Guest OS fails to load the kernel.

Symptoms:

• Virtual machines halt at the GRUB prompt.
• A black screen appears with a blinking cursor at the GRUB stage.
• The virtual machine's /vmfs/volumes/datastore_name/vm_name/vmware.log file shows no disk or hardware errors.
• Virtual disks are mounted and network-connected at the ESXi level, but the boot process does not progress.

Environment

VMware vSphere ESXi 8.x
VMware vCenter Server 8.x

Cause

The snapshot revert can result in a mismatch between the bootloader's pointers (stored in the Master Boot Record or EFI partition) and the actual filesystem state on the virtual disk.

If the OS update modified the disk blocks where the kernel or GRUB configuration resided before the snapshot was taken, the revert may leave the boot sector pointing to invalid or corrupted disk blocks, preventing the bootloader from locating the kernel.

Resolution

Engage the OS vendor to troubleshoot and repair the Guest OS bootloader configuration.