Unplug all non-essential USB devices, update or remove outdated drivers (especially storage, graphics, Wi-Fi and antivirus), uninstall third-party antivirus, free at least 30 GB, update the BIOS, and retry using the Installation Assistant or Media Creation Tool.

0xC1900101, explained

Codes starting with 0xC1900101 are rollback errors from Windows Setup. The second part shows the stage: 0x20017 means a failure in the safe-OS phase (often during boot into setup), 0x30018 during the first boot, and 0x40017 during the second boot. Nearly all of them come back to a driver that won’t load in the new version.

The setup logs at C:\$Windows.~BT\Sources\Panther\setuperr.log often name the driver.

Symptoms

  • “We couldn’t install Windows 11/10. 0xC1900101 - 0x20017” (or 0x30018, 0x40017, 0x4000D).
  • The PC restarts during the upgrade, then rolls back.
  • Feature update offered repeatedly but never completes.

What causes 0xC1900101

  • Incompatible or outdated drivers (storage, graphics, network, audio).
  • Third-party antivirus or disk-encryption software.
  • Connected USB devices, card readers or docks.
  • Insufficient disk space or outdated BIOS.

Try these fixes

  1. Disconnect peripheralsUnplug everything except keyboard, mouse and display: USB drives, printers, docks, card readers, external disks.
  2. Update drivers and BIOSInstall the latest chipset, storage, graphics and network drivers and BIOS from the PC maker. Remove old drivers for hardware you no longer use.
  3. Remove antivirus and VPNsUninstall third-party security and VPN software (you can reinstall after the upgrade).
  4. Free up spaceKeep at least 30 GB free on C:. Use Settings → System → Storage → Cleanup recommendations.
  5. Repair Windows firstRun DISM and SFC (command below).
  6. Read the setup logOpen C:\$Windows.~BT\Sources\Panther\setuperr.log and look for driver (.inf/.sys) names near the failure.
  7. Upgrade with the official toolUse Microsoft's Installation Assistant or Media Creation Tool, choosing to keep files and apps.

Command

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Elevated Command Prompt; restart afterwards before retrying the upgrade.

How to tell it worked: winver shows the new Windows version and the upgrade doesn't roll back.

Avoiding it in future

Update drivers and BIOS before major upgrades and remove legacy software you no longer need.