Windows 11 upgrade initiated via Windows Updates gets stuck in the "downloading..." stage, and always on 8%. Rebooting the PC and restarting the update does not help, it starts downloading from 0, and gets stuck again at 8%.
The issue was resolved by installing the update using Windows 11 Installation Assistant. The only complication is that the Assitant will fail if you run it while the update is already initiated via Windows Updates. To work around this, pause Windows updates, reboot the PC and run the Windows 11 Installation Assitant again.
Windows 10 Pro
DELL Vostro 3710