I'm trying to upgrade from Windows 10 to Windows 11, and I need to convert the disk from MBR to GPT using the mbr2gpt tool. Microsoft support suggested that I format my drive and reinstall Windows, but I've heard that it's possible to do this without formatting. I need to switch to UEFI in my BIOS for the upgrade, but every time I attempt the conversion, I get an error saying 'Cannot find room for the EFI system partition.' I have about 60 GB free on my C drive (disk 0) but I'm confused about whether I need unallocated space. Here's a link to my [disk management screenshot](https://imgur.com/MzrntE2). It feels like I'm hitting a wall at every turn!
1 Answer
It sounds like you have all your space allocated, which is why you're getting that EFI partition error. To fix this, you’ll need to shrink your C: drive by about 500 MB to create unallocated space for the EFI partition. Make sure to back up important data just in case. In Disk Management, right-click on C:, and select 'shrink volume' to reduce it by 500 MB. Once you do that, you should be able to proceed with the conversion.
I tried shrinking my C: drive, but it won’t let me! It shows zero available to adjust, even with 60 GB of free space. Do I really need to format my C drive for this?