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Installing OS X Snow Leopard Server on an i5- or i7-based Macbook Pro fails with the error: The CPU has been disabled by the guest operating system (1026103)

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  • Cannot install Mac OS X Server Snow Leopard in a Fusion virtual machine
  • Installing Mac OS X 10.6 Server on a virtual machine fails
  • You see the error:

    The CPU has been disabled by the guest operating system.


This article explains the limitations of running OS X Snow Leopard Server as a guest on a Macbook Pro with an i5, i7, Nehalem, or Westmere processor.


This issue occurs because Mac OS X Server versions earlier than 10.6.4 do not support the i5, i7, Nehalem, or Westmere processors.
You cannot install OS X Server version 10.6.3 or earlier on a physical mac with one of those processors or on a virtual machine running on a Mac with one of those processors.
To work around this issue, use one of these options:
  • Use an installation disk with Snow Leopard 10.6.4 or later.
  • Create the virtual machine on a different Mac and run Apple Software Update. After OS X 10.6.4 is installed, move the virtual machine to the Mac with the i5, i7, Nehalem, or Westmere processor.
  • Add this line to the .vmx to mask the CPU before attempting to install or update. Once the install/update is complete, remove the line from the .vmx.

      cpuid.1.eax = "0000:0000:0000:0001:0000:0110:1010:0101"

    For more information on editing your .vmx file, see Editing the .vmx file for your Fusion virtual machine (1014782).

See Also

Update History

10/01/10 - Updated list of unsupported processors. 06/28/2011 - added steps to mask CPU with line in .vmx - kadamson

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  • 11 Ratings