ISO Build 26063 fails to boot in Hyper-V - but why?

Iron Contributor

Edit 2: Feedback Hub Link

Host is Windows 11, new empty virtual machine, 8 cores, 20480 MB RAM, network connected, rest default, AMD 5950x, trying to boot

Windows_InsiderPreview_Server_vNext_en-us_26063.iso, MD5 D6F8AEE061B689606F22F6A80A383142

and I get this - Hit a key after three of six dots, and it skips to PXE:



So I swap to Windows_InsiderPreview_Server_vNext_en-us_26040.iso, and it instantly works!



Anybody else having the same effect? Did something change which I fail to see? I would LOOOOVE to get into the bug bash, hoping the deduplication corruption in insider and Server 2022 would finally be noticed and fixed, but it does not even boot!

Looks like I have to install 26040 first (missed the 26052 download, was sick) and then upgrade by running setup.exe from the virtual DVD.


EDIT: Just tested, exactly the same on a Lenovo Laptop with i5-10210U CPU with Windows 10 Enterprise, 26063 iso does not boot, 26040 iso does.

7 Replies


yes, me too, the same. so i did a build 26058, and within a running instance,..
did a clean setup.exe from the 26063 build


Also on a host win server 26063 it gives the same error (it doesn't detect the keyboard orso)


Another alternative, is:
- use a copy vhdx of a working windows installation
- shift F2 safe boot
- repair, go to command prompt
- type D: (your build 26063 iso)
- run setup.exe

The upgrade path does not seem to work in my case. I have to use the VHDX version I guess. Quite a bummer for "Use This Build For Bug Bash".

they revamped the setup/install. if you run the setup as i described, you see a brand new setup action menu, i never have seen before.


just install an older version ISO build first

and after it (re)boots, press F2 / repair -> SAFE boot -> command prompt -> DRIVE D: 


what will work for sure

I run now the newest WServer Build 26063 in Hyper-V. (and a nested one as well)

works okey, but indeed won't boot when having the Windows_InsiderPreview_Server_vNext_en-us_26063.iso attached

it looks it doesn't detect the keyboard quick enough
it's pretty nice (but not working very good)

Same here, cannot boot to the 26063 ISO using Hyper-V on Server 2022 Datacenter.

@Joachim_Otahal This is a known issue for 26063 described here: if you downloade the vhdx instead of the ISO you can use the vhdx for a VM on Windows Server 2022 based Hyper-V to test Windows Server 2025 Build 26063

I only see the normal announcement, and not the comment try you link to.
best response confirmed by Karl_Wester-Ebbinghaus (MVP)
Fixed in 26080.
1 best response

Accepted Solutions
best response confirmed by Karl_Wester-Ebbinghaus (MVP)