Windows Longhorn build 4040

Windows Longhorn build 4040 is a Milestone 6 build of Windows Longhorn and is one of the last builds for that milestone. Grabberslasher first gave the details of this build on his UX.Unleaked blog. On 23 January 2020, this build was listed on a BetaArchive thread by the aforementioned user to be released to its FTP, and was released on 31 January 2020, alongside build 4002 and build 5356. This build is one of the last builds to include the Plex theme, together with the main compile of 4042.

Overall, this build has a very similar feature set to builds 4038 and 4039.

Setup
Although setup altogether is mostly similar to previous builds of Longhorn, the numeral and clock sprites now no longer contain a transparent background.

Features

 * Much of the interface remains similar to that of build 4038 due to Lab04's use of older code, likely from the main lab builds. This can be seen in areas such as File Explorer, where the back, forward, favorite and My Computer icons are identical to build 4038.
 * Related to Lab04's use of older code, the service  does not exist, which means theming cannot be easily enabled/disabled.

Installation
Some copies of this build's installation media cannot be booted normally due to a call to a non-existent index in the  by. To install this build in this case, either upgrade from a previous build or use a WinPE from a previous build.

Safe Mode
Safe Mode does not log you on due to the login process change in build 4032, as it will result in. This was later fixed in Windows Longhorn build 4042 (main).

Upgrade

 * It is currently not possible to upgrade to this build. After the second reboot, Windows will corrupt the registry and will fail to boot, causing the error   when upgrading from most builds prior to this one.
 * When upgrading from build 4028 ~ build 4039, lsass.exe terminates with a critical error, and the system will become stuck in a bootloop. The only workaround is to reinstall Windows. This bug is persistent until build 4053.