BUG: Installing Microsoft Windows Server 2025 fails (related to NUMA / CPU- & Memory Hotplug)

[nvanaert]

Hello everyone,

I'm experiencing issues installing Microsoft Windows Server 2025. Whenever I try to install this operating system, the installer goes up to 15% and then just shows a message: "Windows server installation has failed.", no other useful information.

Has anyone experienced this and how to resolve this issue?

What I've tried so far:
- Three different Microsoft Windows Server 2025 ISO's (all of them show the exact same problem)
- Switching from VirtIO SCSI to SATA (to make sure the VirIO drivers were not causing issues)
- Two different VirtIO driver versions
- Switching from CPU type host to x86-64-v2


I'm running Proxmox 9.1.4 on a ZFS backed store.

 

[nvanaert]

Update: I've got past the installer. It's likely a bug, related to NUMA or CPU / Memory hotplug as those are the features that I've turned off.
Update 2: Once the installation is done I can turn on NUMA and CPU / Memory Hotplug and I do not seem to be having any issues (as in the system seems to boot fine)

 

[nvanaert]

Update 2: I've tested this on 2 more Proxmox 9.1.4 hosts (which are not in a cluster) and can replicate this exact behavior, so most definitely a bug.

 

[nvanaert]

Another update: I've verified the checksums of the ISO's just to be sure and all of them matched, so there's no corrupted ISO's at all (even when uploaded from the GUI).

 

[dviske]

@nvanaert I'm also having this issue at the moment, both on 9.1.1 and 9.1.5. In my case it's only happening when I'm using an Autounattend.xml file to automatically install it as part of a CI workflow, but you might find this useful in troubleshooting:

Once the error prompt pops up, hit Shift+F10 to open a command prompt, cd into X:\Windows\Panther and there should be a file you can open (either use `more` or notepad) and you'll likely have some kind of an error description there. How helpful it is seems to vary, but it's a place to start.