https://kags.me.ke/post/virtualbox-to-hyper-v/
- Launch VirtualBox
- Select Virtual Media Manager from the File menu
- When Virtual Media Manager window opens, select the VM file you want to migrate and click on Copy button
- When the Copy Virtual Hard Disk window opens, click on ExpertMode button to enable selecting required options on one screen.
- Under Hard disk file type, select VHD (Virtual Hard Disk)
- Wait for the copy process to complete
Convert vhd to vhdx
- Launch Hyper-V Manager
- Under Actions, select Edit Disk…
- Click Next on the ‘Before You Begin’ screen
- Browse for the copied file. The file will be having a file extension of vhd. Select the file and click Next button.
- On the Choose Action window, select Convert and click Next button
- Select VHDX format and click Next
- Select Dynamically expanding and click Next
- Select a name and location for the file and click Next
- Click Finish and wait for the conversion process to complete