Cannot update windows 11 to 24H2 - CPU not supported

[Cloudboy]

Hello,

For some reason i cannot get a number of my windows 11 pro vm updated to 24H2.

One of them started the update via windows updates but stopped and i get the same when trying to update via the setup.exe on the DVD.

I have tried a number of CPUs. The KVM64 and a number of the x86-64 CPUs. None of them are working.

Odd thing is that two of the VM did update with no issue.

 

[Moayad]

Hi,

I have tried a number of CPUs. The KVM64 and a number of the x86-64 CPUs. None of them are working.

Even `host` CPU type didn't help? If yes, I would check if the VirtIO have an update.

 

[Cloudboy]

Hi,


Even `host` CPU type didn't help? If yes, I would check if the VirtIO have an update.

Hello Moayad,

indeed using the host cpu resolved the issue. But are there no virtual CPUs that work?

Will the VMs keep getting updates once you move the cpu from the host back to a virtual one?

Thx

 

[Moayad]

Maybe the reason of that, that host CPU ensures full compatibility with updates. and some CPUs works, but future updates could still fail due to missing CPU features. [0]


[0] https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_meltdown_spectre

 

[proxuser57]

I had the same problem upgrading from Windows11 23H2 to Windows11 24H2:



the solution to this issue is creating a custom cpu type.

1. create a new file:
nano /etc/pve/virtual-guest/cpu-models.conf

2. insert this and save the file:

cpu-model: qemu64-popcnt-sse42
flags +popcnt;+sse4.1;+sse4.2;+sse3
phys-bits host
hidden 0
hv-vendor-id proxmox
reported-model qemu64

3. modify your VM:
select the new entry in the cpu type list qemu64-popcnt-sse42

4. Start the VM and the problem should be solved!

 

[thintz3112]

I had the same problem upgrading from Windows11 23H2 to Windows11 24H2:

View attachment 78950

the solution to this issue is creating a custom cpu type.

1. create a new file:
nano /etc/pve/virtual-guest/cpu-models.conf

2. insert this and save the file:

cpu-model: qemu64-popcnt-sse42
flags +popcnt;+sse4.1;+sse4.2;+sse3
phys-bits host
hidden 0
hv-vendor-id proxmox
reported-model qemu64

3. modify your VM:
select the new entry in the cpu type list qemu64-popcnt-sse42

4. Start the VM and the problem should be solved!

Hi,

I have a AMD Ryzen 9 based Host and added the custom CPU model you described above. Unfortunately it is not working. I got an error message:




Maybe the custom CPU type must have different flags for AMD CPUs?

BR
Thomas

 

[thintz3112]

It seems that Microsoft is doing something different. A complete new installation of Win11 24H2 is possible but updating an existing VM is not.

 

[proxuser57]

Hi,

the error message is related to the virtual environment, in this case to the virtual new created CPU, not to the host CPU.
But it is conceivable that the implementation of the CPU parameters is not done correctly because Proxmox VE is not up to date!?
My host CPU is a very old model: intel core i5-6600k, but I'm using Proxmox VE 8.2.7 (not the newest 8.3).

 

[entilza]

Ok any solutions without all these hacks? I set to x86-64-v2-AES. And health check does show that its win11 compatible.

I upgraded virtio to 1.266 (the standard drivers, net, scsi, ballon, serial..)

I am still on q35 8.1. Do I need 9.0?

Must you do the in place iso installation upgrade manually?

UPDATE: I set to x86-64-v3 and the next day I got the upgrade to 24H2 maybe v2 AES would have worked too not sure.

 

[BobhWasatch]

My host CPU is a very old model: intel core i5-6600k, but I'm using Proxmox VE 8.2.7 (not the newest 8.3).

Qemu does not emulate features that don't exist in the underlying CPU. If your CPU isn't W11 compatible there is no way to fake it afaik.

 

[TErxleben]

Hi,


Even `host` CPU type didn't help? If yes, I would check if the VirtIO have an update.

Update virtio-drivers to v266 worked for me.