A feature update or repair install runs for a long time, reaches a certain percentage, and then rolls back with 0xc1900101 followed by a second code. The Windows 10 upgrade error 0xc1900101 almost YYPAUS always involves a driver.

Any code beginning with 0xC1900101 indicates that a driver failed during the installation’s critical phase. Windows then restores the previous version to keep the PC working.

Because the old version comes back intact, you have time to find and fix the troublesome driver before trying again.

Possible Causes

The failing driver is usually connected to one of these:

• Storage controllers or older SSD and RAID drivers.
• Graphics, Wi-Fi, or Bluetooth adapters with outdated drivers.
• External devices, such as card readers, docks, or USB adapters.
• Third-party antivirus or disk encryption software with system-level drivers.

Low disk space can also trigger a rollback with the same family of codes.

Quick Fixes to Try First

Remove the most common obstacles.

1. Disconnect every external device except the keyboard and mouse, including USB drives, printers, and docks.
2. Free at least 20 GB on drive C.
3. Install all pending Windows updates and restart.
4. Update graphics, network, chipset, and storage drivers from the PC manufacturer.
5. Try the upgrade again.

Many 0xc1900101 failures are resolved simply by unplugging accessories and updating drivers.

Advanced Steps for Stubborn Cases

Find the specific driver involved.

1. Open Device Manager and look for any device with a yellow warning symbol. Update or uninstall it.
2. Temporarily uninstall third-party antivirus and disk encryption tools. Windows Security will protect the PC during the upgrade.
3. Run sfc /scannow and DISM /Online /Cleanup-Image /RestoreHealth.
4. Try the upgrade with the Windows 10 Update Assistant or Media Creation Tool instead of Windows Update.
5. If it fails again, look in C:\$WINDOWS.~BT\Sources\Rollback for a file named setupact.log and search it for the driver name mentioned near the failure.

The second code after 0xc1900101 also helps. Codes ending in 20017 or 30018 are widely associated with driver problems during the boot phase of the upgrade.

Before You Go Further: Keep Your Files Safe

Back up your files before every major upgrade attempt. Reinstall your antivirus after the upgrade completes. Do not delete files in the $WINDOWS.~BT folder by hand while setup is running, and avoid unofficial driver packs.

Final Thoughts

Error 0xc1900101 is a driver refusing to cooperate during an upgrade. Unplugging devices, updating drivers, and removing security software solve most cases. The setup logs reveal the exact driver when the simple steps are not enough.

Each failed attempt still leaves the original system in place, so there is no need to rush. Fix one likely cause at a time and retry, rather than changing everything at once.