ESXi Host goes into Not responding state due to unexpected reboot

Products

• VMware vSphere ESXi

Issue/Introduction

vSphere UI shows the server state as "Not Responding" for a while and recovers to "Connected" without intervention.

Uptime of the server suggests the server to be going through a OS reboot cycle. 

Cause

• ESXi host was rebooted due to an erroring hardware component.
• Events from System Event Logs confirm the error state
  • System event logs may have entries similar to the following

Record:1:
   Record Id: 1
   When: 2024-08-22T14:56:18
   Event Type: 111 (Unknown)
   SEL Type: 2 (System Event)
   Message: Assert + Processor IERR
   Sensor Number: 0
   Raw:
   Formatted-Raw: 01 00 02 92 51 c7 66 20 00 04 07 ff 6f 00 ff f1

OR

Record:13:
   Record Id: 13
   When: 2025-06-16T19:45:04
   Event Type: 4 (Minor)
   SEL Type: 2 (System Event)
   Message: Assert + Processor Predictive Failure Asserted
   Sensor Number: 129 
   Raw:
   Formatted-Raw: 0d 00 02 40 74 50 68 20 00 04 07 81 04 01 ff ff

Record:15:
   Record Id: 15
   When: 2025-06-16T19:45:04
   Event Type: 4 (Minor)
   SEL Type: 2 (System Event)
   Message: Assert + Processor Predictive Failure Asserted
   Sensor Number: 176
   Raw:
   Formatted-Raw: 0f 00 02 40 74 50 68 20 00 04 07 b0 04 01 ff ff

Mapping Sensor Numbers will suggest the sensors are related to nay of the CATERR_N, IERR or MCERR

Resolution

Contact the hardware vendor for further diagnostics and resolution.

Additional Information

Viewing System Event Logs

• To view the System Event Logs (SEL), use the command esxcli hardware ipmi sel list from a SSH session of ESXi Server
• Alternatively, there may be reported events in the vSphere UI following the steps listed below:
  
  1. Select a host in the vSphere Client navigator.
  2. Click Monitor tab, and click Hardware Health.
  3. Click SYSTEM EVENT LOG.

Mapping the Sensor numbers reported in the System Log Events. 

• Command esxcli hardware ipmi sdr list from a SSH session of ESXi Server will list the Sensor Data Records providing a mapping of sensors.