Upgrading Windows 10 on a dual-boot system is not that easy. After fetching KB3035583 and KB2952664 and reserving my upgrade copy on Windows 7 Professional x64 the setup still said “Something happened. We can’t tell if your PC is ready to continue installing Windows 10. Try restarting setup.”
The reason for this seems to be dual-boot installations only. First off, change the default boot entry to Windows.
Afterwards I did not want to override Grub with my Fedora 22 installation, but was looking into alternative solutions for error 800703ed. This tip about marking the C: partition as active partition did the trick – the Windows Update is now downloading Windows 10.
Getting ready for installing my Icinga 2 development environment 🙂