Module CPUID Power On Failed

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In this blog, we’ll discuss the Module CPUID Power On Failed error and steps to fix this error for the virtual machine. The complete error looks like this:

Error: Task failed on the server: Module ‘CPUID’ power on failed or failed to power on virtual machine module ‘cpuid’ power on failed.

in the vSphere console, under virtual machine Tasks & Events tab.

I have faced this error because there were some changes made by the user in the CPU core and sockets in the virtual machine. There was a mismatch in the number of core and sockets. It was preventing them to power on the VM. I saw the above-mentioned error in the task manager while troubleshooting it.

CPU identification (CPU ID) masks control the CPU features visible to the virtual machine’s guest operating system.

Let’s first understand the basic concepts of vCPU core and sockets.

Virtual CPU Configuration

A virtual machine with ESXi 7.0 Update 1 and later compatibility can have up to 768 virtual CPUs. You can change the number of virtual CPUs while your virtual machine is powered off. If virtual CPU hot add is enabled, you can increase the number of virtual CPUs while the virtual machine is running.

You can add, change, or configure CPU resources to improve virtual machine performance. You can set most of the CPU parameters when you create virtual machines or after the guest operating system is installed. Some actions require that you power off the virtual machine before you change the settings.

VMware uses the following terminology. Understanding these terms can help you plan your strategy for CPU resource allocation.


The CPU, or processor, is the component of a computer system that performs the tasks required for computer applications to run. The CPU is the primary element that performs computer functions. CPUs contain cores.

CPU Socket

A CPU socket is a physical connector on a computer motherboard that connects to a single physical CPU. Some motherboards have multiple sockets and can connect multiple multicore processors (CPUs).


A core contains a unit containing an L1 cache and functional units needed to run applications. Cores can independently run applications or threads. One or more cores can exist on a single CPU. To know more about CPU Configuration click here.


In order to fix this issue and get the VM back online, I simply changed it with below required vCPU configurations:

Number of virtual sockets: 1

Number of cores per socket: 16

Total Number of vCPU: 1 x 16 = 16*

*The Total number of vCPU is the sum of the number of cores x the number of sockets.

From the misconfiguration state.

To fix your problem you can reconfigure it as the number of sockets in multiple of x2 ( max depends on the Licensing) and cores per socket multiple of x2. Definitely, it will fix your issue on Module CPUID Power On Failed. Let us know in case of any further questions.

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