change a Proxmox Virtual Environment (PVE) virtual machine running Windows Server Standard 2022 from Legacy (SeaBIOS) to UEFI (OVMF)

Malvern Masiye

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Mar 26, 2026
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Microsoft is updating the Secure Boot certificates originally issued in 2011 to ensure that Windows devices continue to verify trusted boot software. Because our servers are still running in Legacy BIOS mode, we must transition them to UEFI boot mode to maintain full Secure Boot compatibility. Therefore, we need the correct method to change a Proxmox Virtual Environment (PVE) virtual machine running Windows Server Standard 2022 from Legacy (SeaBIOS) to UEFI (OVMF).Can you assist with this on our server without losing data
 
I don't think it will work properly unless you make changes by running commands like the ones below on the Windows side.

That's not something you should ask Proxmox about.

bcdboot /l en-US /s /f ALL

*To be honest, I don't even think the partition styles (gpt/mbr) are the same, so I don't think I can do it.
 
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it's same as baremetal,
it's not a really Proxmox side.
You will find tutos online.
System disk need conversion to gpt, then make EFI boot partition to create EFI boot files.
BTW, Legacy Boot / SeaBIOS is not Secure Boot capable, and have not certificates.
 
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You can create virtual machines freely on PVE. Isn’t the safest approach to create a virtual machine yourself and test whether it works?

If someone tells you it’s possible but it doesn’t actually work, you’re the one who ends up in trouble...

As far as PVE controls are concerned, steps 5 through 10 are correct.

Besides, I don’t think the other items listed there have anything to do with PVE. If you’re asking on the Microsoft forums, that’s definitely the right place to go.
 
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