ESXi Host Not responding: Unexpected Reboot or hung due to hardware failure

Products

• VMware vCenter Server

Issue/Introduction

ESXi hosts may experience a 'Not Responding' state in vCenter or encounter persistent hangs during hardware initialization. This behavior typically indicates underlying hardware faults, such as processor or memory issues.

• vSphere Client reports the ESXi host as "Not Responding" and fails to recover.
• The host may appear hung, requiring a force reboot or power cycle to restore connectivity.
• Following a reboot, the host experiences a hang during hardware initialization, failing to boot into the ESXi OS.
• System Event Logs (SEL) confirm critical hardware alerts, such as "Processor IERR" or "Sensor Failure Asserted."

Environment

• VMware vSphere ESXi 8.x
• VMware vSphere ESXi 9.x
• Hardware: All platforms, including Cisco UCS

Cause

Critical hardware alerts (e.g., CATERR_N, IERR, MCERR) indicate that the server processor has detected an unrecoverable internal error, triggering a physical hardware fault state.

Resolution

1. Reboot the ESXi host to attempt recovery.
2. Review System Event Logs (SEL) to map sensor data:
   • Run esxcli hardware ipmi sel list via SSH.
   • Alternatively, navigate to Monitor > Hardware Health > SYSTEM EVENT LOG in the vSphere Client.
3. Use the command esxcli hardware ipmi sdr list to map Sensor IDs to physical components.
4. Engage the hardware vendor immediately for diagnostics based on the identified sensor errors.

Additional Information

• For assistance with log retrieval, refer to Collecting diagnostic information for VMware ESXi using vSphere Client.
• If you need to escalate, Create and Manage a Support Case.