Force Upgrade of VMware ESXi with Unsupported Processor

Posted on 20-Mar-2023 by krylon

When trying to upgrade an ESXi host using the console, I received the error below. In this case I was attempting to upgrade to version 7 Update 3k.

[HardwareError]
Hardware precheck of profile ESXi-7.0U3k-21313628-standard failed with warnings: <CPU_SUPPORT WARNING: The CPU in this host is not supported by ESXi 7.0.3. Please refer to the VMware Compatibility Guide (VCG) for the list of supported CPUs.>

The error will prevent the upgrade from continuing. However, you can force the upgrade of a system with a legacy processor using these steps:

  1. In the root file system of ESXi, edit /bootbank/boot.cfg using vi
  2. On the line that starts with kernelopt=, add the following to the end: allowLegacyCPU=true
  3. Save the file and reboot the host
  4. Then attempt the upgrade again (e.g.,  using esxcli software profile update)
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