"Failed - Module 'NumVCPUs' power on failed" error powering on a virtual machine

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides information on the error: Failed - Module 'NumVCPUs' power on failed.

Symptoms:

• The host uses an AMD processor
• The virtual machine has more than 128 vCPUs
• You see an error similar to:

Failed - Module 'NumVCPUs' power on failed
This virtual machine cannot be powered on because the current configuration does not support 256 CPUs. Decrease the virtual CPU count to 128 or enable EFI firmware and IOMMU support.

Environment

VMware vSphere ESXi 7.0.x
VMware vSphere 7.0.x
VMware vSphere ESXi 6.7
VMware ESXi 6.7.x

Cause

For ESXi hosts with AMD processors, virtual machines are currently limited to 128 vCPUs.

Introduced in ESXi 7.0 Update 1, virtual machines on ESXi hosts with AMD Processors may have more than 128 vCPUs (up to a maximum of 256 vCPUs), but requires the use of virtual hardware version 18.

NOTE: Virtual machines configured to use earlier virtual hardware versions will not support more than 128 vCPUs on AMD processors.

Resolution

To resolve this issue:

• Option 1: upgrade the virtual machine to use virtual version 18 or later
• Option 2: reduce the number of assigned vCPUs to not exceed 128

NOTE: In order to use 128 CPUs, the virtual machine must utilize EFI boot configuration.