Virtual machine CPU reconfiguration fails with configSpec.numCoresPerSocket error

Products

• VMware vSphere ESX 8.x

Issue/Introduction

When you attempt to reconfigure the number of CPUs for a virtual machine, the task fails with the following error message in the vSphere Client.

A specified parameter was not correct: configSpec.numCoresPerSocket

Environment

VMware vSphere 8.0

Cause

This issue occurs because the specified total number of CPUs is not evenly divisible by the configured Cores per Socket value.

Resolution

For virtual machines with hardware version 20 or later, you can configure the CPU topology. For the procedure to configure this setting, refer to Configure the CPU Topology of a Virtual Machine.
To resolve this issue and ensure the total CPU count is evenly divisible by the configured "Cores per Socket" value, perform one of the following actions.

• Specify a total CPU count that is a multiple of the configured "Cores per Socket" value.
• Set "Cores per Socket" to Assigned at power on.