PSOD - "Machine Check Exception" System has encountered a Hardware Error - Please contact the hardware vendor

Products

• VMware vSphere ESXi

Issue/Introduction

• Purple diagnostic screen(PSOD) occurs on an ESXI host with the below back trace and Machine check exception message


  Machine Check Exception on PCPU## in world ######:nsx-appctl
System has encountered a Hardware Error - Please contact the hardware vendor

  SRAR Excp G7 BI Sb988880808180134 AO M86 PO/0 Cache Hierarchy: Level 0 Data Cache DataRead Error

  cr0=0x80010031 cr2=0x39a0c95000 cr3=0x4085897800 cr4=0x142768
FMS=06/55/7 uCode=0x5803901
frame=0x452940505eb0 ip=0x428034c17872 err=0x12 rflags=0x10216

  

Environment

• VMware vSphere ESXi 8.x

Cause

The Machine Check Architecture (MCA) is a CPU feature designed to detect and report hardware anomalies. When the hardware detects a critical or fatal condition, it raises a Machine Check Exception (MCE). These exceptions are considered severe and unrecoverable, which leads to an expected ESXi host crash, often resulting in a Purple Screen of Death (PSOD).
In this scenario, the MCE was categorized as an SRAR (System Reset Assert Register), which denotes:

• Uncorrectable: The error cannot be automatically corrected by hardware.
• Recoverable: A system-level action could theoretically mitigate the issue.
• Action Required: Specific corrective steps, such as terminating the thread accessing the affected Memory Page Number (MPN), are needed

The faulty thread was executing within the vmkernel context the ESXi host was unable to isolate or terminate it. This results in the MCE being escalated to a fatal system error, leading to a crash.

Resolution

• Reboot the Host: Restarting the ESXi host may temporarily restore functionality if the issue was caused by a transient hardware event.
• Engage Hardware Vendor: Contact your server hardware vendor with the captured MCE/PSOD data. A thorough hardware-level investigation is required to identify the root cause of the MCE and assess if hardware replacement or firmware updates are necessary.