Windows 2025 Standard 24H2.11 (iso release of sept 25) crash on reboot with "INACCESSIBLE BOOT DEVICE 0x7B" in XCP 8.2.1 and XCP 8.3

[francesco-maria]

@dinhngtu on my machine there isn't any xen tools installed because was freshly installed and the system doesn't end the first boot. it execute the windows partitioning and file copy, then crash at first boot of the installed system.

[acebmxer]

@dinhngtu same mine where two fresh VMs fresh install of server 2025. Older iso works newer iso does not. For me the newer iso the system rebooted 2 maybe 3 times then crashed to a hard power off of the vm.

Again no xen tools installed as os never finished installing on a fresh vm. no OS upgrade.

[flakpyro]

@dinhngtu Well that is slightly concerning! Ill be sure to not remove Xen Tools on any of these VMs until we can get this resolved. We have a handful of production server 2025 VMs that im now slightly worried about! I should note that last week we did update them to version 9.4.2 of the tools, which tends to require 2 reboots to fully install and we didn't run into any issues.

[dinhngtu]

I've narrowed down the problem to a set of patches. Will continue to diagnose.

[acebmxer]

Just tested Win 11 25H2 iso just released today. No issues with fresh install.

Management tools installed and Citrix PV drivers installed via windows update.

[Pilow]

@acebmxer did you test latest Xen Tools ?

https://www.xenserver.com/downloads#lightbox-20160

7 days old though

[acebmxer]

@Pilow

Did dirty upgrade left all boxes checked and vm is setup to update drivers via windows update....

I have rebooted vm and restarts no issues.

[dinhngtu]

The cause has been found, and a fix is under way. Stay tuned.

[flakpyro]

@dinhngtu Thats great news!

[dinhngtu]

Hi all, here's a pre-build of the fix for anyone who wants to test (8.3 only):

wget https://koji.xcp-ng.org/repos/user/8/8.3/xcpng-users.repo -O /etc/yum.repos.d/xcpng-users.repo
yum update --enablerepo=xcp-ng-ndinh1

[francesco-maria]

@dinhngtu will be released also for 8.2.1?

[olivierlambert]

8.2.1 is EOL: https://xcp-ng.org/blog/2025/09/16/xcp-ng-8-2-lts-reached-its-end-of-life/

[Andrew]

@dinhngtu On a quick test, the ISO boots and installs. When the VM boots from the HD it crashes (and on reboots).

Updating XCP 8.3 with qemu-4.2.1-5.2.12.2~fixvwc1.1.xcpng8.3.x86_64 solves the issue and the installed windows image boots correctly without any additional changes.

[olivierlambert]

That's great! \o/

[francesco-maria]

@olivierlambert this problem can cause a crash on update of windows 2025 VM on xcp-ng 8.2.1 or remains only a problem for fresh install?

[olivierlambert]

8.2 is EOL, and also IDK how it's affected by this issue.

[dinhngtu]

@francesco-maria I haven't determined what exact conditions would trigger the issue. It seems to only happen on new installations for now, but it could very well change in the future. Though as long as you keep the Xen drivers installed, things should be OK.

[francesco-maria]

@dinhngtu Thanks for info. I config that manual apply of fix solve the problem on my 8.3.
I only chance the yum update in yum update --enablerepo=xcp-ng-ndinh1

[dinhngtu]

Hello all, the new test build qemu-4.2.1-5.2.12.2~fixvwc2.1.xcpng8.3 is now available.

If you have tested the fix before, you can update with this command:

yum update --enablerepo=xcp-ng-ndinh1

[Andrew]

@dinhngtu Same results with the updated qemu-4.2.1-5.2.12.2~fixvwc2.1.xcpng8.3.x86_64. The Win2025 VM (without Xen tools) fails to boot correctly using stock XCP 8.3 but starts correctly with the fixvwc patch. (no actual performance or other testing done).