windows vm crashing / hanging

J

jamesmb1

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Nov 26, 2025
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We have a Windows Server 2025 VM that has hung or crashed a couple of times over the past few months, requiring a reboot of the VM to recover.
This is running on Proxmox VE 9.1.1.

What I've checked so far:
  • It seems to happen during a quiet period between 4am and 8am, with no scheduled events or backups occurring within an hour of the issue starting.
  • No sign of any issues in Windows event logs, just a "recovered from unexpected shutdown" entry after the manual reboot.
  • No log entries in journalctl near the time of the issue.
  • No hardware or storage errors in Proxmox or iDRAC.
  • The node hosting the VM is only using around 60% of its total memory.
  • The VM is using local storage, and other VMs on the same storage are not having any issues.

I did notice the CPU graph was reporting a strange, fairly flat amount of cpu usage during the time it was frozen / crashed.

Any pointers on where I should look to find what could be causing this would be appreciated.


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Hi there,

Here is how I proceed when I have come across similar situations.

First check your VM setup - this may sound obvious but on occasions I've missed small details that lead to bigger problems.

* Verify the CPU type (host vs default vs kvm64). Some Windows Server builds can misbehave with certain emulated CPU models.
* Make sure you’re using VirtIO drivers for disk and network. Outdated or mismatched drivers can cause hangs without clear logs.
* Look at ballooning/NUMA settings : if memory ballooning is enabled, try disabling it temporarily to see if stability improves.
* Check if you’re using QEMU Guest Agent. If not, install it, it can provide better visibility and control.

The Windows 2025 best practices - https://pve.proxmox.com/wiki/Windows_2025_guest_best_practices from the official docs has a lot of important information - go through it in detail :)

Fabián Rodríguez | Le Goût du Libre Inc. | Montreal, Canada | Mastodon
Proxmox Silver Partner, server and desktop enterprise support in French, English and Spanish
 
MagicFab said:
Hi there,

Here is how I proceed when I have come across similar situations.

First check your VM setup - this may sound obvious but on occasions I've missed small details that lead to bigger problems.

* Verify the CPU type (host vs default vs kvm64). Some Windows Server builds can misbehave with certain emulated CPU models.
* Make sure you’re using VirtIO drivers for disk and network. Outdated or mismatched drivers can cause hangs without clear logs.
* Look at ballooning/NUMA settings : if memory ballooning is enabled, try disabling it temporarily to see if stability improves.
* Check if you’re using QEMU Guest Agent. If not, install it, it can provide better visibility and control.

The Windows 2025 best practices - https://pve.proxmox.com/wiki/Windows_2025_guest_best_practices from the official docs has a lot of important information - go through it in detail :)

Fabián Rodríguez | Le Goût du Libre Inc. | Montreal, Canada | Mastodon
Proxmox Silver Partner, server and desktop enterprise support in French, English and Spanish
Click to expand...

Can confirm the cpu type is set as host, using the latest VirtIO drivers with disk/network hardware set to VirtIO versions and the QEMU guest agent is running. I read through the best practices wiki and it looks like we are following all of those.

Will try disabling memory ballooning and see if it has an impact but it could be 1-2 weeks before we see it happen again.
Is it normal to not see any sign of a crash like this in the proxmox logs or is there additional logging that can be enabled for this?
 
If the VM crash is not Proxmox related (hardware, memory, irq, qemu, etc.) you won’t see any entries.

Did you check the Windows log files? And how is your VM configured?
 
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