Posts Tagged ‘Ryzen’

Minisforum MS-A2 HOW TO: Fix the Failed to Update CPU#0 Microcode PSOD with ESXi 8.0.3i ESXi 8.0u3i

Wednesday, March 11th, 2026

Minisforum MS-A2 HOW TO: Fix the Failed to Update CPU#0 Microcode PSOD with ESXi 8.0.3i ESXi 8.0u3i

 

HOW TO: Fix “Failed to update CPU#0 microcode” PSOD on ESXi 8.0.3i (Minisforum MS-A2)

In this guide from Hancock’s VMware Half Hour, I demonstrate how to fix the
Purple Screen of Death (PSOD) error:

“Failed to update CPU#0 microcode”

This issue occurs when installing or booting VMware ESXi 8.0 Update 3i (ESXi 8.0.3i)
on the Minisforum MS-A2 mini workstation.

ESXi 8.0.3i, released on 2 March 2026, includes security fixes for
CVE-2025-15467, an OpenSSL vulnerability. If you are running ESXi and have not
patched yet, you should update as soon as possible.

However, this update also includes new AMD CPU microcode updates, which currently
appear to trigger a PSOD during boot on the Minisforum MS-A2 platform.


The Problem

When booting the ESXi 8.0.3i installer (for example from Ventoy) on the
Minisforum MS-A2, the system may fail during boot with the following PSOD message:

The system has found a problem on your machine and cannot continue.

Failed to update CPU#0 microcode

This prevents ESXi from completing the boot process or installer launch.


Why This Happens

The ESXi 8.0.3i update includes newer AMD microcode updates intended to improve
security and stability. Unfortunately, these updates currently appear to be
incompatible with the MS-A2 platform, which results in the microcode update failing
during boot.

When the microcode update fails, ESXi halts the boot process and displays the PSOD.


The Workaround

Until VMware releases a permanent fix, the issue can be worked around by using a
kernel boot option during ESXi startup.

Steps to Fix

  1. Boot the ESXi 8.0.3i installer.
  2. When the ESXi boot screen appears, press Shift + O.
  3. This opens the ESXi boot options.
  4. Add the required kernel option shown in the video.
  5. Press Enter to continue booting.

With the boot option applied, ESXi should boot successfully on the Minisforum MS-A2.


Video Walkthrough

Watch the full walkthrough below where I demonstrate the issue and apply the workaround.


What You Will Learn

  • What changed in ESXi 8.0.3i
  • Why AMD microcode updates trigger a PSOD
  • How to reproduce the issue during boot
  • The Shift + O ESXi boot workaround
  • How to confirm the fix works successfully

Credits

Huge thanks to members of the VMware community who investigated and documented this issue:

  • Stephen Wagner
  • Patrick Kernstock
  • vAndu
  • Martin Gustafsson

Their research and testing helped identify the workaround shown in this video.

Resources:


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Minisforum MS-A2 – The Ultimate #Homelab Server for VMware vSphere, VVF, and VCF?

Monday, June 30th, 2025

Lately, it feels like every VMware vExpert has been posting photos of their compact lab servers — and I’ll be honest, I was starting to feel left out.

So, I joined the club.

I picked up the new Minisforum MS-A2, and I’ve not looked back. This isn’t just another NUC alternative — it’s a serious powerhouse in a tiny chassis, perfect for VMware enthusiasts building or upgrading their vSphere, VVF, or VCF test environments.

Let’s dig into what makes this little beast a perfect addition to any #homelab setup in 2025.

Hardware Highlights – Not Your Average Mini PC
The MS-A2 isn’t just punching above its weight — it’s redefining what’s possible in a compact lab node.

Key Specs:
CPU: AMD Ryzen™ 9 9955HX – 16 cores / 32 threads of Zen 5 power

Memory: Dual DDR5-5600MHz SODIMM slots – up to 96GB officially, but…

Storage:

3× M.2 PCIe 4.0 slots (22110 supported)

Supports U.2 NVMe – great for enterprise-grade flash

Networking:

Dual 10Gbps SFP+ LAN

Dual 2.5GbE RJ45 ports

Wi-Fi 6E + Bluetooth 5.3 (going to replace this with more NVMe storage!)

Expansion:

Built-in PCIe x16 slot (supports split mode – ideal for GPUs, HBAs, or NICs)

This is homelab gold. It gives you the raw compute of a full rack server, the storage flexibility of a SAN box, and the network fabric of a modern datacenter — all under 2L in size.

How I Configured Mine – still sealed in box as I write – video incoming!
I purchased mine barebones from Amazon, and — as of writing — it’s still sealed in the box. Why? I’m waiting for all the parts to arrive.

Most importantly, I’ll be upgrading it with:
128GB of Crucial DDR5-5600 SODIMMs (2×64GB) — pushing beyond the official spec to see just how much performance this little box can handle.

Once everything’s here, I’ll be unboxing and assembling it live on a future episode of Hancock’s VMware Half Hour. Stay tuned if you want a front-row seat to the full setup, testing, and VMware lab deployment.

Perfect for VMware Labs: vSphere 8/9, VVF, and VCF
Whether you’re testing ESXi on bare metal or running full nested labs, this spec ticks every box.

ESXi Bare Metal Capable
The Ryzen 9 9955HX and AMD chipset boot vSphere 8.0U2 and 9.0 Tech Preview cleanly with minimal tweaks. Use community networking drivers or USB NIC injectors if needed.

VVF / VCF in a Box
If you’re exploring VMware Validated Foundation (VVF) or want a self-contained VCF lab for learning:

16C/32T lets you run nested 3-node ESXi clusters + vCenter + NSX-T comfortably

128GB RAM gives breathing room for resource-heavy components like SDDC Manager

PCIe 4.0 + U.2 = blazing fast vSAN storage

Dual 10Gb SFP+ = NSX-T overlay performance lab-ready

Community Validation – I Was Late to the Party
Fellow vExpert Daniel Krieger was ahead of the curve — writing about the MS-A2 months ago in his excellent blog post here:
sdn-warrior.org/posts/ms-a2

Then vExpert William Lam added his voice to the conversation with a guide to running VMware Cloud Foundation (VCF) on the MS-A2:
williamlam.com/2025/06/vmware-cloud-foundation-vcf-on-minisforum-ms-a2.html

Seeing both of them validate the MS-A2 pushed me over the edge — and I’m glad I jumped in.

Setup Tips (Soon!)
Once the unboxing is done, I’ll share:

BIOS tweaks: SVM, IOMMU, PCIe bifurcation

NIC setup for ESXi USB fling and 10GbE DAC

Storage layout for vSAN and U.2/NVMe configs

Full nested VCF/VVF deployment guide

Considerations
Still not officially VMware HCL — but community-tested

Ryzen platform lacks ECC memory — standard for most mini-PC builds

PCI passthrough needs thoughtful planning for IOMMU groupings

Ideal Use Cases
Nested ESXi, vSAN, vCenter, NSX labs

VVF deployment simulations

VCF lifecycle manager testing

Tanzu Kubernetes Grid

NSX-T Edge simulations on 10GbE

GPU or high-speed NIC via PCIe slot for advanced lab scenarios

Final Thoughts
The Minisforum MS-A2 with Ryzen 9 9955HX is a serious contender for the best compact homelab system of 2025. Whether you’re diving into vSphere 9, experimenting with VVF, or simulating a full VCF environment, this mini server brings serious firepower.

It may still be in the box for now —
—but soon, it’ll be front and center on Hancock’s VMware Half Hour, ready to power the next chapter of my lab.

Join the Conversation
Got an MS-A2 or similar mini-monster? Share your specs, test results, or VMware experience — and tag it:

#VMware #vSphere #VCF #VVF #homelab #MinisforumMSA2 #10GbE #vExpert