Hyper-V: Unable To Start a VM From ISO File

Your ISO file is most probably blocked by Windows.

Start by right-clicking the file => Properties. Click Unblock => OK/Apply.

Try now, and if that doesn't work, create a copy of the ISO file and try again.

If that doesn't work, Try a different machine.

The solution to this problem is very simple: just make a copy of the ISO file and use that instead!

The issue is that Hyper-V does not support booting from sparse ISO files. A file may be sparse if it was downloaded via BitTorrent or other parallel download managers. A regular Windows Explorer file copy will create a non-sparse copy, which Hyper-V supports.

To check whether or not a file is sparse, Right Click, select Properties, and look at the Details tab. If P is present under the Attributes, the file is sparse and will fail to boot:

Screenshot of Details tab with Attributes section highlighted