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Cannot change the guest operating system selection of a virtual machine in ESXi 5.1 (2020801)

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  • If you have an existing virtual machine registered to an ESXi 5.1 host and are trying to change the selected guest operating system for the virtual machine using the vSphere Web Client, the guest operating system selector is greyed out and you cannot change the value
  • This issue occurs even though you have appropriate permissions for the virtual machine


With vSphere 5.1, you cannot change the guest operating system selection for an existing virtual machine using the vSphere Web Client.

The guest operating system that you select affects the number of virtual CPUs, amount of memory, virtual NIC types, and virtual disk controller types available to the virtual machine.

To avoid impacting an existing virtual machine, these values do not change when you change the selected guest operating system.

If you change the guest operating system selection and subsequently install a new guest operating system, the virtual machine might be using incorrect virtual hardware devices, which can lead to performance and stability issues. This configuration is not supported.


This issue is resolved in vCenter Server 5.5. You can download the latest vCenter Server release from the VMware Download Center.
If you are on vSphere 5.1 and you made an incorrect guest operating system selection when you created the virtual machine, or if you need to change the selection for any reason, create a new virtual machine. This ensures that the correct virtual hardware devices are selected for your guest operating system.

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