Q: How can I convert a VHD to a VHDX?

A: There are two ways you can convert a regular virtual hard disk (VHD) to the new VHDX format found in Windows 8 and Windows Server 2012: by using Windows PowerShell or by using the Hyper-V Manager graphical interface.

Using PowerShell, enter this command:

Convert-VHD

as in my example:

Convert-VHD -Path d:tempsource.vhd -DestinationPath d:tempdestination.vhdx

Using Hyper-V Manager, start the Edit Disk action and select the source VHD file. Then, under the action, select Convert, then select the VHDX format.