To recover a ESXi host for which a critical failure was detected during system boot.

Products

• VMware vSphere ESXi

Issue/Introduction

This article will help to find the cause of the boot failure.

Symptoms:

After bootup/upgrade, the host fails to exit maintenance mode. The user can also observe:

• Event on VC UI:

"A critical failure was detected during system boot. The host is currently not able to exit maintenance mode and run workloads."                                 

• Message on host UI (summary page):

"A critical failure was detected during system boot. The host cannot currently run workloads"

• Manual attempt to exit maintenance mode also fails with same error:

#esxcli system maintenanceMode set -e=0

A general system error occurred: Cannot exit maintenance mode due to failure during boot.

 

Environment

VMware vSphere ESXi 8.0.x

VMware vSphere ESX 9.0

Cause

There could be different reasons for the boot failure.

Example: Failed to repartition the disk while upgrading from 6.5/6.7 to 8.0U2  or failure during bootbank expansion while upgrading from 8.x to 9.0

Resolution

To find the cause of the boot failure login to the host and look for the relevant alert message in /var/run/log/vmkwarning.log file and follow the KB mentioned in it. The same alert message can be found on the sysAlert shell (press Fn+option+F11) on ESXi DCUI.

Example: YYYY-MM-YYT09:59:20.467Z Al(177) vmkalert: cpu0:1000079885)ALERT: An error occurred while backing up VFAT partition files before re-partitioning. This might be due to VFAT corruption. Please refer to KB 345227 for steps to remediate the issue.

Workaround:

The workaround would be specific to the cause of the boot failure. Please refer to the KB specific to the failure.