I ran into this Hyper-V subtlety, so I figure I’ll share it here and make it easier to find with a search. If you try to import a Hyper-V image and the import fails, you will not be able to use the same files to try the import again. Hyper-V actually deletes and alters files as part of the import process.
The error you’ll likely see is “Import failed. Import failed. Unable to find virtual machine import files under location … You can import a virtual machine only if you used Hyper-V to create and export it.” At face value this error is infuriating since you are trying to import a Hyper-V export, but the fact that you’re running the import for the second time means that Hyper-V does not consider your source to be valid.
The lesson here is don’t try and import your exported Hyper-V image without first making a backup copy. If you have a backup, you can just copy over the small files again and not have to export or copy the large image files a second time.