How to convert a VHDX file to VHD?

You can do that conversion with VirtualBox :

VBoxManage.exe clonemedium "input_file.vhdx" "output_file.vhd" --format VHD

Default Path to VBoxManage.exe

C:\Program Files\Oracle\VirtualBox\

Before anything, make a backup of the original .VHDX, just in case.

You said you have Windows 7. In that case, you can easily convert VHDX to VHD with PowerShell.

Go to "Run..." (Windows + R) and type Powershell.

Then, in the PowerShell command line, type the command PS C:\> Convert-VHD –Path YOUR VHDX PATH –DestinationPath YOUR DESTINATION PATH

It should be converted then.

You can find additional information about the Convert-VHD command here.

To convert vhdx to vhd use the free StarWind V2V Image Converter

I made the same mistake, when creating the Virtual disk from the physical with Disk2VHD, there is a check box at the top right (second down) that is ticked by default to create a vhdx, Remove this check and it will create a vhd instead.