# hyper-v cannot boot Gen2 guest from Windows 2012 R2 or Windows 8.1 x64 ISO - file format not supported, Gen1 works fine

• ### Question

• I am new to Gen2 Hyper-V and so far I simply can't use it, because I am unable to install any (supported) guest OS from an ISO ...

So far I tried that on:

1. my HP Z230/i4770 workstation (Secure Boot disabled) host running Windows 8.1 Pro x64 (with Hyper-V feature enabled), can't boot any VM with supported OS ISO.

2. my home desktop/i3770K (secure Boot enabled) host running Windows 8.1 Pro x64, same result, error during VM boot from ISO, quoted below.

Synthetic SCSI controller (instance blah blah) Failed to Power on with Error 'The version does not support this version of file format'

Gen1 guests of course work perfectly fine with those ISOs, because emulated DVD IDE picks up the official Enterprise Evaluation ISO of either Windows Server 2012 R2 or Windows 8.1 x64 Enterprise, perfectly fine and all works OK in Legacy boot mode.

When I create a new guest and select Gen2, then no matter if I check or uncheck the Secure Boot in virtual Boot Order options for the guest (while setting the SCSI DVD at top of course), it simply doesn't work, always same error. I tried first connecting to VM to see if it prompts for key press, but it doesn't, the error is instant on Power on when (supported) ISO image is selected to be booted.

I verified that both of official Enterprise Evaluation ISO's of either WS2012r2 and W8.1x64 are bootable in both the UEFI mode (Secure Boot enabled) and Legacy BIOS mode using a physical computer.

What am I missing here???

• Edited by Sunday, February 9, 2014 7:10 PM
Saturday, February 8, 2014 3:11 AM

• FYI, above is wrong! it's not about linking ISO to virtual DVD or selecting "Install OS later", it's all about the location of the ISO file and share permissions on parent folder!

I was actually suspecting several issues, but haven't had time to test it, was thinking about issues like assigning (or not) some of initial settings during Gen2 VM creation, e.g.:

-Network connection through virtual switch or Not Connected (make no different if assigned or not)

-Memory above 4096MB (makes no difference if < or > 4096MB)

-ISO file location (makes huge difference!)

The ISO file CANNOT be placed on network share OR in shared folder on same local drive as the VHDX file (works fine if parent folder is not shared).

I can now replicate the issue easily every time and it always fails with file format unsupported message whenever I have the ISO file located either on remote network share, or (fails the same way too) when I have the ISO file placed locally (on host drive) when simply a parent folder is shared... must be some permissions issue... and a pretty dumb one considering that in production environments nearly everything is placed on remote file servers ...

... so the moral of the story is, if you want to install Gen2 VM in win8/2012 hyper-V then you must copy the ISO file to Hyper-V host drive AND make sure the parent folder is not shared. works every time now! :)

• Edited by Wednesday, February 12, 2014 5:09 AM
• Marked as answer by Wednesday, February 19, 2014 5:21 PM
Wednesday, February 12, 2014 5:06 AM
• Copying fixed my issues since I downloaded from the TechNet Eval Center and it puts a "parse" attribute on the file.  Copying with Windows Explorer removes the attribute: http://blog.ctaggart.com/2013/12/bug-of-day-couldnt-mount-file-in.html
• Marked as answer by Wednesday, October 1, 2014 9:17 PM
Wednesday, September 24, 2014 5:23 PM

### All replies

• anybody?
• Proposed as answer by Wednesday, July 30, 2014 9:52 PM
• Unproposed as answer by Wednesday, July 30, 2014 9:52 PM
Sunday, February 9, 2014 7:02 PM
• it makes zero sense, but I got it to work, flawlessly now :)

It seems that culprit was in the way I created all test Gen2 Guests in Hyper-v (feature of Windows 8.1 in my case, but it's same as one in Windows 2012R2) ... I was always selecting "Install OS later" option and then trying to link the ISO image to virtual DVD (on SCSI interface) in VM settings ... I googled and googled and all I could find was an advice to move ISO file to different drive, I tried all local ones, tried NAS and file shares, nothing worked, always the same error stating the file format problem blah blah.

Then I deleted all those not working Gen2 guests, did the testing on Gen1 guests (all worked of course, no matter if ISO was placed locally or on network) and then re-created Gen2 guest ... but this time I immediately selected OS ISO which I carefully placed beforehand on same drive as hyper-v vhdx drive ... bam, worked with zero issues ... that is kind of crazy, but hey it works, LOL!

will re-test this theory soon.

• Edited by Wednesday, February 12, 2014 5:08 AM
Tuesday, February 11, 2014 8:43 PM
• FYI, above is wrong! it's not about linking ISO to virtual DVD or selecting "Install OS later", it's all about the location of the ISO file and share permissions on parent folder!

I was actually suspecting several issues, but haven't had time to test it, was thinking about issues like assigning (or not) some of initial settings during Gen2 VM creation, e.g.:

-Network connection through virtual switch or Not Connected (make no different if assigned or not)

-Memory above 4096MB (makes no difference if < or > 4096MB)

-ISO file location (makes huge difference!)

The ISO file CANNOT be placed on network share OR in shared folder on same local drive as the VHDX file (works fine if parent folder is not shared).

I can now replicate the issue easily every time and it always fails with file format unsupported message whenever I have the ISO file located either on remote network share, or (fails the same way too) when I have the ISO file placed locally (on host drive) when simply a parent folder is shared... must be some permissions issue... and a pretty dumb one considering that in production environments nearly everything is placed on remote file servers ...

... so the moral of the story is, if you want to install Gen2 VM in win8/2012 hyper-V then you must copy the ISO file to Hyper-V host drive AND make sure the parent folder is not shared. works every time now! :)

• Edited by Wednesday, February 12, 2014 5:09 AM
• Marked as answer by Wednesday, February 19, 2014 5:21 PM
Wednesday, February 12, 2014 5:06 AM
• The fix above this post doesn't apply for me. The fix in my case was to create a copy of the iso file (ISO location doesn't matter)  that contains the operating system, and simply reattaching it to the VM.
Friday, June 6, 2014 1:41 PM
• The fix above this post doesn't apply for me. The fix in my case was to create a copy of the iso file (ISO location doesn't matter)  that contains the operating system, and simply reattaching it to the VM.
Strange thing but this fixed it for me too.
Tuesday, June 17, 2014 5:53 PM
• Move the iso to a different volume on your hypervisor. Point your VM to that new location and start it.
Wednesday, July 30, 2014 9:53 PM
• Copying fixed my issues since I downloaded from the TechNet Eval Center and it puts a "parse" attribute on the file.  Copying with Windows Explorer removes the attribute: http://blog.ctaggart.com/2013/12/bug-of-day-couldnt-mount-file-in.html
• Marked as answer by Wednesday, October 1, 2014 9:17 PM
Wednesday, September 24, 2014 5:23 PM
• Copying fixed my issues since I downloaded from the TechNet Eval Center and it puts a "parse" attribute on the file.  Copying with Windows Explorer removes the attribute: http://blog.ctaggart.com/2013/12/bug-of-day-couldnt-mount-file-in.html

interesting! and must be true! I just checked and ISO files I kept on network share were in deed having the P attribute (APL to be specific) while the local copy of file on hyper-v host had only A attribute.

However I think MS must have fixed something in meantime, because I have just tried mounting the ISO over network to hyper-v gen2 guest and it worked fine (even tho there was P attribute on it) ... the funny part however is once I unmounted such ISO from guest, then the file disappeared from network share ... it was deleted ... hmmm ...

EDIT:

double checked the network share, actually a DFS share (2 file server members in it), and the ISO file was removed from one of servers, sill resides on the other one. not sure what happened.

• Edited by Wednesday, September 24, 2014 9:20 PM
Wednesday, September 24, 2014 9:16 PM
• Copying fixed my issues since I downloaded from the TechNet Eval Center and it puts a "parse" attribute on the file.  Copying with Windows Explorer removes the attribute: http://blog.ctaggart.com/2013/12/bug-of-day-couldnt-mount-file-in.html

that is precisely the root cause.

just tested it on new ISO download of Win 10 x64 Technical Preview (same problem with mounting such ISO to hyper-v guest gen2 & synthetic scsi dvd). copying the file to another folder removes the P attribute and then it works fine.

This must have been what I accidentally did when copying ISO files over network (from DFS share to local drive) hence why I though it worked only in local folder and not in networked share.

Wednesday, October 1, 2014 9:20 PM
• I had the same problem. Just making a copy of the ISO and pointing to the new copy worked for me.
Wednesday, November 5, 2014 2:30 AM
• Hello folks,

In my case, the fact that the file was created as sparse file seemed to be the issue. I resolved as follows:

Unblock the file if it's blocked:
﻿

Run these commands in an administrative command prompt:

set file=D:\path\to\yourfile.iso
attrib -R "%file%"
fsutil sparse queryflag "%file%"
fsutil sparse setflag "%file%" 0

Afterwards, the VM should boot from the ISO successfully. Good luck and enjoy! Please let us know if this helped!

-V

• Proposed as answer by Friday, July 17, 2015 5:07 PM
Friday, July 17, 2015 5:03 PM
• You can just use the cmdlet:  UnBlock-File

And be done with it.  no cryptic fsutil command line commands.

Brian Ehlert
http://ITProctology.blogspot.com
Learn. Apply. Repeat.

Friday, July 17, 2015 7:12 PM
• Hello Everyone,

I have tried the solution from VBdP Solipsis and suggestion by Brian.

No more ISO image issue on my HYPER-V running on Win 8.1 (Enterprise).

However the Boot Failed -

Errors:

Boot Failed. EFI SCSI Device.

Boot Failed. EFI Network.

Boot Failed. EFI SCSI Device.

No Operating System was Loaded. Press a key to retry the boot sequence...

Experts, please suggest where I`m going wrong?

Regards, Dematri

Monday, August 24, 2015 2:52 AM
• The installation ISO should boot as either a Generation1 or a Generation2 VM.

However, a Genertion1 installed VHD will not boot as a Generation2 VM, and vice versa.

I am not clean what your particular symptoms are.

Personally, I frequently use Convert-WindowsImage to generate a generalized image for either Generation1 or Generation2 VMs.  (you get Generation1 by default).

Brian Ehlert
http://ITProctology.blogspot.com
Learn. Apply. Repeat.

Monday, August 24, 2015 3:17 AM
• Great! that works for me. :)

Sunday, June 26, 2016 5:48 PM
• Ok, here it is 12/2017 and I'm having the same issues. I tried loading with several different configs, with .iso in different locations, and and with Secure Boot on and Off. All resulted in the same error message as you have noted. The only thing that worked for me was to build the VM in GEN1 and it worked first time like a charm, no issues. I'm kind of new to Hyper-V, so I need to decide if it is worth any further investigation, or if I should just go forward with Gen 1?

Tuesday, December 12, 2017 5:46 AM

I have tried the solution from VBdP Solipsis and suggestion by Brian.

No more ISO image issue on my HYPER-V running on Win 8.1 (Enterprise).

However the Boot Failed -

Errors:

Boot Failed. EFI SCSI Device.

Boot Failed. EFI Network.

Boot Failed. EFI SCSI Device.

No Operating System was Loaded. Press a key to retry the boot sequence...

Errors:

Boot Failed. EFI SCSI Device.

Boot Failed. EFI Network.

Boot Failed. EFI SCSI Device.

No Operating System was Loaded. Press a key to retry the boot sequence...

Tuesday, December 12, 2017 5:48 AM
• thanks a lot

the unblock fixed the problem

Tuesday, September 4, 2018 1:08 PM