Installing Windows 11 without 8.3 short file name support

Right, yep. ReFS is nice for large data volumes, virtualization (it's really good for VHDX storage), high-availability, stuff like that. NTFS is still the workhorse file system for Windows. As g-man mentioned, you can boot from ReFS, but I'm not sure why you would.

Maybe not possible from Disk Manager, but it could be possible with a third-party utility. You can test it in a virtual machine. Install Windows 11 in GPT (UEFI boot) and then convert the Windows partition from NTFS to ReFS. Try to boot into Windows and post your results. I won't do it, just out of curiosity.

There is no conversion tool, like a mbr2gpt for ReFS. ReFS doesn't support NTFS alternate data streams, so a lot of file metadata would go missing.

If it is going to screw the file system just to be less vulnerable to errors or whatever, no thanks! I will stay with NTFS forever.

Thank you all for your contributions. They were very instructive and enlightening.

I found the following reg entry in TenForums.com for ReFS file system. I learned from you that I could not convert to ReFS on already-installed Windows. For test purposes anyway, I applied the reg entry and restarted Windows. Windows couldn't restart, of course. This was Windows 11 with stripped 8dot3 short file names on Hyper-V VM and corruption of Windows was not important.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MiniNT
AllowRefsFormatOverNonmirrorVolume (DWORD)
(delete MiniNT key) = disable
1 = enable