How to Fix Windows Error 0xC1900101

What Causes This?

Windows error 0xC1900101 usually points to a problem during a major Windows update or upgrade, often caused by a bad driver, leftover update files, or not enough free disk space. It can also happen when security software, external devices, or corrupted system files interfere with setup. In most cases, Windows starts the upgrade, fails partway through, and then rolls back to the previous version.

Common Symptoms

• Windows update or upgrade fails and shows 0xC1900101
• The PC restarts several times, then says it is undoing changes
• Feature updates like moving to a new Windows version will not install
• The upgrade gets stuck at a certain percentage, then rolls back
• You notice very low free space on the system drive

How to Fix It Manually

1. Disconnect unnecessary devices

   • Unplug external hard drives, USB hubs, printers, SD cards, and other non-essential devices.
   • Leave only your keyboard, mouse, monitor, and internet connection.
   • Restart your PC and try the update again.

2. Free up space on your system drive

   • Press Windows + E to open File Explorer.
   • Click This PC and check free space on Local Disk (C:).
   • If space is low, press Windows + R, type cleanmgr, and press Enter.
   • Select drive C:, then check items like Temporary files, Windows Update Cleanup, Delivery Optimization Files, and Recycle Bin.
   • Click OK, then Delete Files.

3. Remove old Windows update files

   • Press Windows + I to open Settings.
   • Go to System > Storage > Temporary files.
   • Check items such as Temporary Windows installation files, Windows Update Cleanup, and other temporary files you do not need.
   • Click Remove files.
   • Restart the PC after cleanup.

4. Update or remove problematic drivers

   • Right-click the Start button and choose Device Manager.
   • Look for devices with a yellow warning icon.
   • Expand categories like Display adapters, Network adapters, and Storage controllers.
   • Right-click a device and choose Update driver.
   • If the error started after a recent driver change, choose Properties > Driver > Roll Back Driver if available.
   • You can also temporarily uninstall third-party antivirus software before retrying the upgrade.

5. Repair corrupted system files

   • Click Start, type cmd, then right-click Command Prompt and choose Run as administrator.
   • Run this command:

     sfc /scannow

   • When it finishes, run:

     DISM /Online /Cleanup-Image /RestoreHealth

   • Restart your PC after both scans complete.

6. Reset Windows Update components

   • Open Command Prompt as administrator again.
   • Run these commands one at a time:

     net stop wuauserv
     net stop bits
     net stop cryptSvc
     ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
     ren C:\Windows\System32\catroot2 catroot2.old
     net start wuauserv
     net start bits
     net start cryptSvc

   • Restart the computer and try Windows Update again.

7. Run the upgrade with a clean boot

   • Press Windows + R, type msconfig, and press Enter.
   • On the Services tab, check Hide all Microsoft services, then click Disable all.
   • Open the Startup tab and click Open Task Manager.
   • Disable non-essential startup apps, restart the PC, and retry the upgrade.

Fix It Automatically with Kudu

If you do not want to hunt through temporary files, update leftovers, and disk space issues manually, Kudu can do the cleanup for you. It helps remove junk files, clear old Windows update data, and free space that often contributes to 0xC1900101 upgrade failures.

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