Upgrade Windows 10 to Windows 11 on Proxmox with an Unsupported CPU

Published 11/08/2026

Description

Windows 10 has reached end of support, but upgrading an existing Windows 10 virtual machine to Windows 11 on Proxmox is not always straightforward. Contents: 0:00 - Introduction 0:16 - Description 1:23 - The Problem 2:26 - The Solution 6:19 - Conclusion In this video, I upgrade an older Windows 10 VM running on Proxmox to Windows 11. The VM runs on a Dell PowerEdge R6415 with an older AMD EPYC 7551P processor, and the standard CPU configurations—including KVM, host, and generic EPYC profiles—do not satisfy the Windows 11 compatibility checker. The challenge is that Windows 11 checks more than TPM availability. It can also reject the CPU presented to the virtual machine, even when the server remains perfectly capable for day-to-day virtualization workloads. This tutorial is useful if you are using: Windows 10 end-of-support messaging Using the Windows 11 Installation Assistant Checking compatibility with the Microsoft PC Health Check application Why the default Proxmox KVM CPU is rejected Why exposing the host CPU may still fail Windows 11 validation Testing standard EPYC CPU profiles in Proxmox Why newer EPYC Rome profiles may not start on older physical EPYC hardware Creating a custom Proxmox CPU model Presenting a compatible CPU model to the Windows guest Hiding the virtual-machine environment from the Windows compatibility check Adding the CPU flags needed to start the VM successfully Completing the Windows 10 to Windows 11 upgrade The custom CPU model is defined in the Proxmox CPU-model configuration, allowing the VM to report a Windows 11-compatible CPU profile while retaining compatibility with the actual older AMD EPYC host processor. This approach is useful for homelab users and administrators who run Windows virtual machines on older server hardware and encounter the “processor isn’t currently supported for Windows 11” message. Before applying changes in production, take a tested VM backup or snapshot a