Posts Tagged ‘Virtualisation’

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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Part 7: DIY UNRAID NAS “BY THE POWER OF UNRAID” THE SCRET REVEALED

Saturday, December 6th, 2025

By The Power Of UnRAID – The Secret Reveal Of ESXi And Windows 11 VMs

For the last few episodes of Hancock’s VMware Half Hour, we have been quietly building something a little different.
On the surface it looked like a simple DIY UNRAID NAS project and a couple of Windows 11 P2V demonstrations.
In reality, everything was running inside virtual machines on an UnRAID host.

In Part 7 of the DIY UNRAID NAS series, we finally pull back the curtain and reveal what has really been powering the lab:
UnRAID running nested ESXi and Windows 11 VMs, complete with PCI passthrough.
This post walks through the idea behind the episode, how it ties back to earlier parts, and why I keep saying,
“By the power of UnRAID.”

Recap: Parts 6, 100 and 101

If you have been following along you will have seen:

  • Part 6 – Installing and testing Samsung 990 PRO NVMe drives in the Intel NUC based NAS.
  • Part 100 – Performing P2V migrations of Windows 11 systems.
  • Part 101 – Continuing the Windows 11 P2V work and refining the process.

In those episodes the star of the show appeared to be a physical Windows 11 machine and a separate ESXi host called ESXi052.
In Part 7 we reveal that this was deliberately misleading. Both the Windows 11 system and the ESXi host were in fact virtual machines.

The Secret: Everything Was A Virtual Machine

Part 7 opens by jumping back to those previous episodes and then revealing the twist:

  • The “physical” Windows 11 machine you saw on screen was actually a Windows 11 VM.
  • The ESXi host ESXi052 that we used for P2V work was also a VM.
  • The same VM was used in Part 6 when we installed and tested the NVMe drives.

In other words, the entire recent run of content has been driven by virtual machines on UnRAID.
The NVMe upgrades, the Windows 11 P2Vs, and the ESXi demonstrations were all happening inside VMs, not on bare metal.

Windows 11 With PCI Passthrough

One of the key enabling features in this setup is PCI passthrough on UnRAID.
By passing through hardware devices such as NVMe controllers or GPUs directly into a Windows 11 VM,
we can test and demonstrate “bare metal like” performance while still keeping everything virtual.

In the video we show Windows 11 running with PCI passthrough on UnRAID, giving the VM direct access to the hardware.
This is ideal for lab work, testing, and for scenarios where you want to push a homelab system without dedicating separate physical machines.

Nested ESXi 8.0 On UnRAID

The next part of the reveal is nested virtualization.
UnRAID is hosting a VMware vSphere Hypervisor ESXi 8.0 VM which in turn can run its own VMs.
This gives an incredibly flexible environment:

  • UnRAID manages the storage, cache, parity and core virtual machine scheduling.
  • ESXi runs nested on top for VMware specific testing and lab work.
  • Windows 11 runs as another VM on the same UnRAID host, with PCI passthrough as needed.

With this approach a single Intel NUC based NAS can simulate a much larger lab
while still being compact and power efficient.

By The Power Of UnRAID

To celebrate the reveal I created a fun meme inspired by the classic “By the power of Grayskull” scene.
In our version, “By the power of UnRAID” raises ESXi and Windows 11 high above the NUC,
showing that UnRAID is the platform empowering the whole setup.

Whether you are running nested ESXi, Windows 11 with PCI passthrough, or a mixture of containers and VMs,
UnRAID makes it straightforward to combine storage flexibility with powerful virtualization features.

The Power Of UnRAID In The Homelab

The big takeaway from Part 7 is simple:

  • A single UnRAID host can consolidate multiple roles: NAS, hypervisor, and workstation.
  • You can experiment with ESXi 8.0, Windows 11, and PCI passthrough without building a large rack of servers.
  • By keeping everything virtual you gain snapshots, flexibility, and the ability to rebuild or clone systems quickly.

For homelab enthusiasts, students, and anyone who wants to learn VMware or Windows 11 in depth,
this approach offers a lot of power in a very small footprint.

Watch The Episode

If you want to see the full walkthrough, including the moment the secret is revealed,
watch Part 7 of the DIY UNRAID NAS series on Hancock’s VMware Half Hour.
You will see exactly how the Windows 11 VM, the nested ESXi host, and UnRAID all fit together.

Conclusion

Part 7 closes the loop on a long running lab story.
What looked like separate physical systems were really virtual machines,
carefully layered on top of an UnRAID powered NAS.
By the power of UnRAID, we have been able to demonstrate NVMe upgrades, Windows 11 P2Vs, and ESXi 8.0 testing
all on a single compact platform.

If you are planning a new homelab or want to refresh an existing one,
consider what UnRAID plus nested ESXi and Windows 11 VMs could do for you.

Still Numero Uno at Experts Exchange

Sunday, October 2nd, 2011
Still on top at Exchange Experts on 2 October 2011

Still on top at Exchange Experts on 2 October 2011

Still On top in October 2011 after approx 4 months, this Year! Can leakim971 catch up!

Experts Exchange (EE) is a membership-based online “ask an expert” site for computer and IT related questions that was founded in 1996. Experts Exchange (EE) enables people with technology problems to quickly and easily solve their problems by collaborating with experts from around the world. Experts Exchange (EE) is the #1 resource on the web for solving IT related problems, pop over and take a test drive, and meet the Experts.

Checkout How it Works.

The 1st Certified Virtualisation Genius at Experts Exchange

Sunday, October 2nd, 2011

On Tuesday, 27 September 2011, I became the 1st Certified Virtualisation Genius at Experts Exchange. Here is a copy of my certificate.

Certified Virtualisation Genius at Experts Exchange

Certified Virtualisation Genius at Experts Exchange

Experts Exchange (EE) is a membership-based online “ask an expert” site for computer and IT related questions that was founded in 1996. Experts Exchange (EE) enables people with technology problems to quickly and easily solve their problems by collaborating with experts from around the world. Experts Exchange (EE) is the #1 resource on the web for solving IT related problems, pop over and take a test drive, and meet the Experts.

Checkout How it Works.

Genius Badges before Virtualisation Badge

Genius Badges before Virtualisation Badge

Genius Badges after Virtualisation Badge

Genius Badges after Virtualisation Badge