[new] - Windows Server 2008 Build 6003

Important Note: Windows Server 2008 (RTM) originally was Build 6000. Service Pack 2 (SP2) brought it to Build 6002. Build 6003 is not a new feature release; it is a servicing update that changes the kernel build number to allow continued security updates.

Method C: Registry

• Path: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
• Value: CurrentVersion = 6.0
• Value: CurrentBuildNumber = 6003

Patching & Support

• Build 6003 only appears on systems enrolled in the ESU program (paid or extended support).
• After ESU ended (January 2023 for most customers, extended to 2024 for some), no new updates increment the build further.
• Microsoft does not provide a “downgrade” to build 6002 once 6003 is installed.

1. What is Build 6003?

• Base Version: Windows Server 2008 Service Pack 2.
• Purpose: When Microsoft ended mainstream support, they released ESU patches. A specific update (KB4493473 / KB4499164) incrementally changed the build number from 6002 to 6003.
• Kernel Change: The build number was updated to ensure that future security patches could be installed correctly on the ESU-supported OS.
• Misconception: It is not Windows Server 2008 R2 (which is Build 7600+). It is strictly 32-bit or 64-bit 2008 (Vista kernel).

4. You Can’t "Remove" 6003

This isn’t a separate service pack. It’s an integral patch. Uninstalling KB4489887 will revert you to Build 6002, but that also removes months of other security fixes. Not recommended unless you have a specific compatibility issue. windows server 2008 build 6003