You have five computers that run Windows 8.1 Pro. You need to perform an upgrade installation of Windows 10 on the computers. What should you do?

imagex.exe applies a pre-captured WIM image to a volume, which is a clean deployment method and does not perform an in-place upgrade that retains the existing OS configuration.

Booting into Windows PE and running setup.exe does not support in-place upgrades because Windows PE is a minimal environment that cannot migrate the existing installation's applications and settings.

Running setup.exe while signed in to Windows 8.1 Pro launches the Windows 10 installer in upgrade mode, which migrates installed applications, user profiles, and settings to the new OS. This is the only method that qualifies as an upgrade installation rather than a clean install. The upgrade path from Windows 8.1 Pro to Windows 10 is fully supported this way via a network share containing the Windows 10 source files.

Booting from a USB drive containing Windows 10 source files starts setup outside of the existing OS, resulting in a clean install rather than an upgrade that preserves user data and applications.