While testing the newly released VMware ESXi 9 in my lab environment, I was seeing the following error during the installation process. This issue popped up right after the system scan and was not letting me do the complete deployment. In this article, I’ll walk you through the cause of the error and how to fix or work around it for lab setup.
VMware ESXi 9 Installer : Error(s)/Warning(s) Found During System Scan : The system encountered the following warning(s) and error(s).
<CPU_SUPPORT ERROR: The CPU on this host is not supported by ESXi 9. Please refer to the Broadcom VMware Compatibility Guide (VCG) for the list of supported CPUs. Please refer to KB 82794 for more details.>
Due to this error I had only 2 option to proceed - either to go back (F9) or Reboot (F11), it won't let me pass through.
First the correct way is to fix the issue using supported CPUs. You can check the supported Processor list on the official Broadcom website https://knowledge.broadcom.com/external/article/318697/cpu-support-deprecation-and-discontinuat.html.
Next since this is my demo lab and I was not intended to make any change in hardware or buy new hardware(CPU). I wanted to utilize the same hardware for POC of ESXi 9. To resolve this, after booting ESXi installer, on the right bottom side you will see option <SHIFT+O: Edit boot options>
Press combination of keyboard key SHIFT+O. You will have to be very quick as this option stays their for only 5 seconds and after it proceeds for booting installer.
Next on the left bottom side below option appear.
<ENTER: Apply options and boot>
> runweasel cdromBoot allowLegacyCPU=true
Type allowLegacyCPU=true and hit Enter key to start booting and loading ESXi Installer.
Update 24-05-2025
Found one more alternative command cpuUniformityHardCheckPanic=FALSE, but it is not tested by me yet.
New system scan now displays a CPU compatibility warning instead of an error. Which allows you to continue with warning. You can go ahead with the installation by selecting the "(Enter) Continue" option. This change might indicate relaxed CPU requirements or added support for previously incompatible processors, but it is not recommended for production environment use.
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