Install error - 0xc1900101

The INACCESSIBLE_BOOT_DEVICE green-screen rollback should be investigated through SetupDiag and the rollback logs first, then the identified storage, chipset, encryption, or filter driver should be updated or removed before retrying build 29695.1001.

Build 29695.1001 does not list this failure as a known issue; Experimental channel builds can nevertheless be unstable and have limited documentation.^1^

1. Identify the driver involved

After the rollback, open this file in Notepad:

C:\Windows\Logs\SetupDiag\SetupDiagResults.xml

Windows Setup runs SetupDiag automatically after an unsuccessful upgrade. Check the final failure recorded in the file, because when multiple failures appear, the last one is typically fatal.^2^

Also examine these rollback files in File Explorer:

C:\$Windows.~BT\Sources\Rollback\setupmem.dmp
C:\$Windows.~BT\Sources\Rollback\*.evtx
C:\$Windows.~BT\Sources\Rollback\setupapi\setupapi.dev.log

$Windows.~BT is hidden, so enable View → Show → Hidden items in File Explorer. Search the SetupDiag result and setupapi.dev.log for a driver filename ending in .sys, a device name, or an extended error such as 0xC1900101-0x20017. Microsoft identifies 0xC1900101 as a generic rollback code usually associated with an incompatible driver; the supplemental rollback files are intended to identify the specific driver.^3^

If the automatic result is missing, download the latest SetupDiag and run it from Command Prompt (Admin):

mkdir C:\SetupDiag
cd /d "%USERPROFILE%\Downloads"
SetupDiag.exe /Output:C:\SetupDiag\Results.log /Verbose
notepad C:\SetupDiag\Results.log

2. Correct the identified component

For the device or .sys file named in the logs:

1. Obtain the latest BIOS/UEFI, chipset, and storage-controller driver from the PC or motherboard manufacturer.
2. If SetupDiag identifies third-party disk encryption, antivirus, backup, virtualization, or storage-management software, uninstall or update that product before retrying.
3. Open Device Manager, locate the corresponding device, and check for a warning icon. Update or uninstall it only when the logs clearly identify it.
4. Restart and retry Windows Update.

Do not randomly uninstall the active SATA/NVMe/RAID controller: removing the driver used to boot Windows can leave the current installation unbootable. Microsoft’s general 0xC1900101 guidance recommends updating third-party drivers and BIOS and correcting Device Manager errors.^4^

Conditional fallback

If no driver is identified:

1. Disconnect nonessential external storage, docks, and USB devices.
2. Temporarily uninstall non-Microsoft antivirus software.
3. Perform a clean boot:
   • Press Win+R, enter msconfig.
   • Under Services, select Hide all Microsoft services, then Disable all.
   • Under Startup, open Task Manager and disable startup items.
   • Restart and retry the Insider update.

If it fails again, preserve SetupDiagResults.xml, setupmem.dmp, rollback event logs, and setupapi.dev.log, then submit them with a Feedback Hub report under Install and Update → Downloading, installing, and configuring Windows Update.

References

1. Windows 11 Insider Experimental (Future Platforms) Preview Build 29695. ...
2. SetupDiag
3. Windows 10 upgrade resolution procedures
4. [Windows 11](https://support.microsoft.com/windows/deployment/install-upgrade/get-help-with-windows-upgrade-and-installation-errors)