ESXi Host rebooted unexpectedly

Products

• VMware vSphere ESXi

Issue/Introduction

ESXi Host rebooted unexpectedly

ESXi was not rebooted via the vCenter or ESXi Client, DCUI, SSH etc

ESXi shows no evidence of PSOD

There was no power outage.

 

Environment

Vmware vSphere ESXi 8.x +

Cause

Cause is unknown at this stage but most likely a hardware problem

None of the ESXi logs show anything specific that would indicate why the host rebooted. VOBD Log and IPMI Logs indicate a possible hardware issue (nothing specific)

Most of the Logs show a 10-15 min gap during the time the ESXi host is being rebooted.

 

 

VOBD Log shows

 YYYY-MM-DDTHH:MM:SS.sssZ In(14) vobd[#######]  [GenericCorrelator] 136564346us: [vob.user.host.poweroff.reason.unavailable] The host is being powered off. 
 The power off was not the result of a kernel error, deliberate reboot, or shut down. This could indicate a hardware issue. 
 Hardware may reboot abruptly due to power outages, faulty components, and heating issues. To investigate further, engage the hardware vendor.

 

IPMI Shows a Soft Off

 

 Record:106:
 Record Id: 106
 When: 2025-11-27T05:42:45
 Event Type: 111 (Unknown)
 SEL Type: 2 (System Event)
 Message: Assert + System ACPI Power State S4/S5: soft-off
 Sensor Number: 170
 Raw:
 Formatted-Raw: 6a 00 02 d5 e4 27 69 20 00 04 22 aa 6f 06 ff ff

Resolution

Given the lack of anything definitive in the ESXI logs like this  - would advise to engage the ESXi hardware vendor

In this initial case -  A case was opened with the hardware vendor, and they found that the BIOS and the Server Platform Services need to be upgraded.