If you've tried to use Boot Camp Assistant to install or upgrade to Windows 10 S, an error appears that says "Windows could not parse or process the unattend file for pass [specialize]."
Your Mac might restart repeatedly as you click through the error messages.
Follow these steps to start up in macOS and begin the Windows installation again:
- Press and hold the power key on your Mac for a few seconds to shut down.
- Wait a few seconds, then press the power key again to turn your Mac back on. Hold down the Option key immediately after turning on your Mac.
- Release the Option key when you see the Startup Manager window.
- Select the macOS startup disk, then click the arrow or press Return.
- Open Boot Camp Assistant and click Continue.
- Click Restore to remove the existing Boot Camp partition.
- Start the installation process again using Windows Home or Windows Pro instead of Windows S.