0xC1900101 – Windows upgrade has been rolled back

During version upgrade, this general reset code often occurs with driver problems. The additional code is important for classification.

Stop if unsure or if a new warning appears. Save your work before changes and ask IT before changing a work device. Never disclose passwords or recovery keys.

Write down the complete code including the suffix, such as 0x4000D, and the Windows version (Windows + R → winver).
Back up your files. Before the next attempt, disconnect unneeded USB devices, but not the mouse, keyboard or the installation media.
Check the appropriate drivers for your model on the PC manufacturer's official support page. Restart. If the upgrade fails again, pass the code and update history on to specialist help.

Test after each step and stop when the issue is solved. Checkmarks are not permanently saved.