The recommended method to convert these disks is to upgrade the operating system to Windows 10 first, then perform the MBR to GPT conversion. So 2k8 sounds like a no no even for an offline conversion.

With Microsoft ending Windows 10 updates on October 14, 2025, millions of users must upgrade to Windows 11. This operating ...

For added security, Windows 11 will forgo the older MBR partition scheme and use GPT instead. That may require users to convert their older hard drives. Here is how to do it.

If you are not able to convert MBR to GPT, and get MBR2GPT failed - Causing backup/restore privilege Issues error, then see this post.

As a leading provider of data recovery, file backup, and disk management solutions, EaseUS has observed that an increasing number of PC users encounter errors such as "Secure Boot is not enabled" or ...