After recent Windows server 2025 cumulative update KB5060842 VPSs don't start with BSOD: UNSUPPORTED PROCESSOR

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Applicable to:

  • SolusVM 2

Symptoms 

  • After recent Windows server 2025 cumulative update KB5060842 VPSs don't start with BSOD:
    SVM_ERROR: UNSUPPORTED PROCESSOR
  • An AMD processor is used on CR.

Cause

Bug in Windows update KB5060842.

The error specifically targets systems configured with CPU type set to “host,” which passes through the actual AMD processor features to the virtual machine.

In SolusVM2 CPU type 'host' is the default configuration.

Resolution

Until Microsoft fixes the issue, apply one of workarounds that suit you more:

Workaround I. If AMD processors are used on all CRs. Workaround II. If AMD processors are used on some CRs only.
  1. Go to Settings > Compute Resources.
  2. In the KVM Settings > Libvirt XML configuration specify:

    CONFIG_TEXT: <cpu mode='custom' match='exact' check='none'>
      <model fallback='allow'>EPYC-Rome</model>
    </cpu>

  3. Settings will be applied automatically for the new virtual machines, for the old virtual machines you may want to trigger the configuration edit, e.g. change the Disk cache mode from writeback to writeback (requires the reboot of VM).

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