Install Setup Dynamic Update KB5135883 before rerunning the Server 2025 scan if the installation media contains the October 2026 update; Microsoft documents this exact Server 2016 → Server 2025 failure with 0x80070003 - 0x40008 and fixes it in KB5135883.^1^
Apply the fix
- Identify the media/update level.
This documented regression applies when Server 2025 installation media includes the October 2026 update, KB5126646. Microsoft does not characterize it specifically as a Legacy BIOS/MBR defect, so the firmware type should not be changed to address this case. - Obtain KB5135883 through one of its supported channels:
- Permit Windows Setup to download Dynamic Update during Setup.
- Download
KB5135883from the Microsoft Update Catalog and apply it to the Server 2025 installation media. - In WSUS, synchronize:
- Product:
Microsoft Server operating system-24H2 - Classification:
Update
- Product:
- Alternatively, use Server 2025 media containing the November 10, 2026 fixes or later.
The November cumulative update also lists the identical Server 2016 → Server 2025 compatibility-check failure as fixed.^2^ - Rerun the scan from an elevated Command Prompt:
D:
setup.exe /auto upgrade /noreboot /eula accept ^
/compat scanonly /compat ignorewarning
echo Exit code: %errorlevel%
Replace D: with the mounted, updated Server 2025 media drive.
The expected result when no compatibility block exists is 0xC1900210; 0xC1900208 indicates an actionable compatibility issue.^3^
What this establishes
- There is a documented Server 2025 Setup regression matching the source OS, target OS, phase, message, and exact
0x80070003 - 0x40008code. - The documented applicability condition is October 2026-updated Server 2025 media.
- The documentation does not establish Legacy BIOS/MBR as the cause.
- A direct, media-based upgrade from Windows Server 2016 to Windows Server 2025 is supported for nonclustered systems; an intermediate Server 2022 upgrade is not required.^4^
Because the unchanged partition layout is successfully resolved by Server 2022 Setup, avoid modifying active flags, partition types, or boot files before testing corrected Server 2025 Setup binaries. Those changes are unnecessary for the documented regression and can make the server unbootable.
If the media predates October 2026 or the corrected scan still fails
That would fall outside the documented KB5135883 condition. Collect the new Panther logs and verify whether the failure remains in GetSystemVolumeNtPath:
-
C:\$WINDOWS.~BT\Sources\Panther\setupact.log -
C:\$WINDOWS.~BT\Sources\Panther\setuperr.log - Latest
CompatData*.xml - Latest
*_APPRAISER_HumanReadable.xml
Dynamic Update should remain enabled so Setup receives current setup and compatibility components. After remediation, repeat the scan and verify that it returns 0xC1900210.^5^
References
- KB5135883: Setup Dynamic Update for Windows Server 2025: November 10, 2026 | Microsoft Support
- November 10, 2026—KB5131080 (OS Build 26100.33822) | Microsoft Support
- Windows Setup Command-Line Options
- Plan your Windows Server upgrade
- Use Windows Setup compatibility scan logs to identify blocking issues