There should be a message about valid MBR and invalid GPT.Type \\.\physicaldrive# on the prompt, replace # with number, usually 0 for a system with single drive.Run gdisk to start the interactive prompt.Change the drive to C: (could be different letter) where the gdisk is located.Boot from the USB drive, press Shift-F10 on the Language selection screen to launch the command prompt.Copy gdisk64.exe or gdisk32.exe to the root of the USB drive containing Windows installer.The Windows binary (less than 1 MB download) can also run on Windows PE, so there's no need to get a live CD or custom bootable drive.
GPT fdisk can convert GPT disk to MBR without data loss, by utilizing the inefficiencies in MBR partition scheme. How do I convert the disk losslessly to GPT without downloading large files, and preferably right from Windows PE? I can download small files from my phone and copy them to the USB drive, but the connection isn't stable enough for downloading a Linux Live USB or paid bootable partition manager. FDISK can easily convert MBR disk to GPT, but only if the disk is empty, while I need to keep the data on other partition, and don't have enough time nor space to back them up first.
Since I don't have a working OS right now, Windows PE is my only hope. If I haven't remove the system partition, I can easily boot to Windows 7 and use third party tools to convert from there.
#Gdisk wipe boot disk windows 01 install
The installer complaint about booting from UEFI and can't install on non-GPT disk. Wishing to just clean install Windows 10 while keeping the data on non-system partition, I made a mistake by booting from Windows 10 installer USB drive, removing the system partition right before trying to start the installation. I get an old laptop with Windows 7 installed.