https://support.microsoft.com/en-us/help/4027554/windows-windows-10-upgrade-assistant-is-stuck-at-99


Windows 10 Upgrade Assistant is stuck at 99%

Applies to: Windows 10

If the progress of Windows Upgrade Assistant is stuck at 99% for more than four hours, here's something you can try. Note: Make sure you follow these steps before you restart your PC. Otherwise, the Media folder might be unavailable.

  • Open File Explorer, type C:\$GetCurrent, and then press Enter.

  • Copy and paste the Media folder to the desktop. If you don't see the folder, select View and make sure the check box next to Hidden items is selected.

  • Restart your PC, open File Explorer, type C:\$GetCurrent in the address bar, and then press Enter.

  • Copy and paste the Media folder from the desktop to C:\$GetCurrent.

  • Open the Media folder and double-click Setup.

  • Follow the instructions to start the upgrade. On the Get important updates screen, select Not right now, and then select Next.

  • Follow the instructions to finish upgrading to Windows 10. After you're done, make sure to install available updates. Select the Start  button, and then select Settings  > Update & Security  > Windows Update > Check for updates.