Why does Windows 10 fail to install on UEFI/GPT laptop?

Solution 1:

I also created a bootable USB to install Windows 10 on a fresh system (as I only had a Mac, I used this great guide), which is also based on a GPT partition table on the USB stick. I ended up with the same error message and was stuck for hours with it.

EricDAltman's answer and the others finally pointed me to the problem and the solution: The windows installer (yes, in 2020! and UEFI is not really new anymore - and all this while using the latest Windows 10 october 2020 iso) get's into trouble with a GPT formatted USB stick and presents the message "windows could not prepare the computer to boot into the next phase of installation". The USB stick's GPT somehow interferes with our HDD/SSD where we wanted to install Windows 10 (this is also why geg's solution worked, since he copied all the installation files to the HDD and unmounted the USB stick which caused the windows installer to work again).

The solution is to simply format the USB stick using MBR partition table instead of GPT - so for me doing this on a Mac first:

diskutil eraseDisk MS-DOS "WIN10" MBR /dev/disk2

And NOT diskutil eraseDisk MS-DOS "WIN10" GPT /dev/disk2 (I guess with other tools like rufus it's simply a configuration option there also).

Solution 2:

In my experience, this has been caused by one of two issues. First I'll offer solutions to a potentially broken installer (which I've experienced a few times over the years). Then I'll comment on the Installation Media's format at the end.

One possibility is a bug in the Disk Partitioning by the Windows installer, in my experience. Over the years I've seen it either utilize the wrong sector sizes or, more commonly, not set the boot partition as active. This is assuming that the failure occurs AFTER the partitions are setup which has been my experience.

To repair this, after Windows Installer sets up the partitions and fails to install, please try the following:

1. Boot with your Install drive mounted and go to the "Repair Options" section
2. Open a Command Line
3. Then type diskpart
4. Verify you only have the one drive by typing list disk
5. Type select disk # with # being the disk you're installing to
6. Then list part which will give you a list of partitions on that disk you have selected
7. Type select part # where # is the boot partition that the installer created but failed to install to
8. Type active to make that the active boot partition for this device
9. Type exit to finish with diskpart and let it save the changes

At this point you should be good to reboot and attempt the install again.

If at this point you're still out of luck, it is likely the installation media you are using. Since you are using a GPT USB drive, it could be conflicting with the installer's attempt to locate proper installation destinations (even with you explicitly stating yours). To remedy this, format the drive as MSDOS (good ol' FAT32) instead of GPT and try again.