Cobalt

Cobalt
Version of Microsoft Windows
Logo
Screenshot
OS familyWindows 11 (NT 10.0)
SemesterCobalt
Architecturex86,[a] x64, ARM64
Replaces
Iron
Replaced by
Nickel

Cobalt is the 21H2 development semester of Windows as a service, the commercial release of which is the original release of Windows 11. Work on Cobalt began in October 2020, although it did not replace Iron in the Dev Channel until December. It was later followed by Nickel in the second half of 2021.

List of known builds[edit | edit source]

For server builds, see Windows Server, version 23H2.
This list only includes builds for the original release of Windows 11 that still had the Windows 10 user experience before reverse integration. For builds that have the new user experience, see Windows 11 (original release) § List of known builds

Pre-Dev Channel[edit | edit source]

Dev Channel (rs_prerelease branch)[edit | edit source]

Dev Channel (co_release branch)[edit | edit source]

Notes[edit | edit source]

  1. Up to build 21390.2025.