Confirmed
- The code belongs to the 0xC1900101 rollback family; it does not identify a specific driver by itself.
Update · reviewed 2026-09-01
0xc1900101 Windows Update diagnostic
Windows Setup rolled back an upgrade after a driver or low-level device interaction failed during setup.
High for the error familyNot confirmed until stage and context are known
Real cases
Resume a saved session — paste a Resume Capsule
The capsule is validated and restored only in this browser. An invalid capsule changes nothing.
Crawlable evidence ledger
What this diagnostic record establishes
Not confirmed
- The code alone does not prove a single root cause.
- It does not justify deleting update caches, changing the registry, or reinstalling drivers as a first step.
Context changes the route
At which stage did the update fail?
Download
Likely layer: Upgrade driver compatibility or device transition
First safe check: Confirm the download boundary before repairing anything
Expected: The extended code and phase narrow the failure before any driver is removed.
Install
Likely layer: Upgrade driver compatibility or device transition
First safe check: Confirm the installation boundary before repairing anything
Expected: The extended code and phase narrow the failure before any driver is removed.
Restart or rollback
Likely layer: Upgrade driver compatibility or device transition
First safe check: Confirm the restart boundary before repairing anything
Expected: The extended code and phase narrow the failure before any driver is removed.
Feature upgrade
Likely layer: Upgrade driver compatibility or device transition
First safe check: Confirm the upgrade boundary before repairing anything
Expected: The extended code and phase narrow the failure before any driver is removed.
Before any second repair step
Verify the observation and preserve the evidence
After the first safe check, record whether the reviewed intermediate result occurred, whether the original problem was retested, and the exact output. An expected observation is not automatically a repair.
Outcome boundaries
- Observed as expected
- Observed something different
- Result unclear
- Could not complete the check
Then separately record whether the original problem still occurs, was not reproduced once, or has not been retested yet. Every session ends in stop, one repeat of the same check, one named missing fact, or escalation—never an open-ended repair sequence.
Evidence fields for this task
- Windows version/buildExample: Windows 11 24H2, build 26100
- KB or feature updateExample: KB5065426 or 24H2 feature update
- Failed stage or percentageDownload, install, restart/rollback, 76%, FIRST_BOOT…
- Extended code or final messagePreserve the final code/message exactly
The browser-local Evidence Pack combines the selected context, safe action, actual observation, sources, review date, missing evidence, and stop boundary. It can be copied or printed without creating an account or uploading a log.
After you perform the safe check
Read the evidence you collected
Paste a short WindowsUpdate.log, CBS.log, DISM, or servicing excerpt and extract timestamps, components, KBs, packages, error codes, and repeated error clusters without uploading the log.
Review trail
Official and first-party sources
- Windows Update error reference Microsoft Learn · primary
- Common Windows Update errors Microsoft Learn · primary
- Windows Update log files Microsoft Learn · primary
- Windows 11 release information and known issues Microsoft Learn · primary
- Microsoft Error Lookup Tool Microsoft Learn · primary