For a Windows 10 upgrade that stops around 35% and rolls back to Windows 7, the supported fixes are:
- Disconnect nonessential hardware Unplug devices such as printers, scanners, speakers, USB drives, external hard drives, and docking stations before trying the upgrade again.
- Install all available Windows updates first Before retrying the upgrade, make sure Windows 7 has the latest important updates and hardware driver updates installed.
- Remove non-Microsoft antivirus or other third-party security software Third-party security software can block the upgrade. Uninstall it before retrying. Make sure installation media and activation information are available so it can be reinstalled later.
- Uninstall nonessential software Older or unnecessary applications can interfere with setup. Remove anything not needed for the upgrade.
- Check Device Manager for driver problems Open Device Manager and look for devices with a yellow exclamation mark. For any problem device, right-click it and choose Update Driver Software or Uninstall.
- Do a clean boot and try the upgrade again Since startup apps were already disabled, use a full clean restart into Windows and then retry the upgrade.
- Repair the disk
Open Command Prompt as administrator and run:
This will schedule a disk repair and require a restart.chkdsk /f C: - Repair system files
Open Command Prompt as administrator and run:
DISM.exe /Online /Cleanup-image /Restorehealth - Make sure there is enough free space Windows needs at least 16 GB free for a 32-bit upgrade or 20 GB for a 64-bit upgrade.
- If the upgrade still fails, contact Microsoft support The Windows upgrade error guidance recommends contacting Microsoft support if the common fixes do not resolve the issue.
Note: chkdsk /f C: and DISM.exe /Online /Cleanup-image /Restorehealth require administrator permissions. chkdsk will modify the disk to repair errors, so save work first and expect a restart.
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