Windows Longhorn build 4000
| Build of Windows Longhorn | |
 | |
| OS family | Windows NT |
|---|---|
| Version number | 6.0 |
| Build number | 4000 |
| Architecture | x86 |
| Compiled on | 2002 |
Windows Longhorn build 4000 is an unleaked build of Windows Longhorn that was mentioned in the setup of Longhorn builds from build 4005 up until build 4033, where it states that a user cannot perform an upgrade installation on a build lower than 4000.