Windows Longhorn build 4086 (lab03_dev)

6.0.4086.lab03_dev.040629-1910
	Build of Windows Longhorn
Version number	6.0
Build number	4086
Architecture	x86
Build lab	lab03_dev
Compiled on	2004-06-29
Expiration date
Timebomb	2004-12-26 (+180 days)
SKUs
	Professional
Product key
	TCP8W-T8PQJ-WWRRH-QH76C-99FBW
About dialog

Windows Longhorn build 4086 (lab03_dev) is a Milestone 7 build of Windows Longhorn. On 23 January 2020, this build was listed on a thread by UX.Unleaked blog founder Grabberslasher to be released to the BetaArchive FTP, and was later released in the tenth set of their 33 Longhorn/Vista builds on 2 February 2020 with its other compiles.^[1]

Changes[edit | edit source]

The setup text during the setup and hardware portions has been changed in this build, which is seen in Windows Longhorn build 4087.

Bugs and quirks[edit | edit source]

Installation[edit | edit source]

As typical of builds in this build range, it tends to take a long time to install and can be unstable.
Various commands in WinPE's command prompt such as formatting a drive will not work due to VSSAPI.DLL being missing.
After the second stage of setup (hardware detection phase), the system will not restart automatically and get stuck on a blank screen with the desktop watermark. Simply reboot the machine to finish the setup.
This build can't be installed in VirtualBox since it will BSOD with an error code of 0x0000021a after rebooting from the second stage of setup. It is recommended to use another hypervisor/emulator instead, such as VMware or QEMU.

Upgrade[edit | edit source]

Attempting to upgrade from other builds is not possible as one of two outcomes may occur:

A bugcheck with error code 0x7E after the second reboot. This is commonly observed when trying to upgrade from non-componentized builds, such as 4074 (via a registry tweak that reports it as a componentized build).
An error during the file copy phase.

Timebomb[edit | edit source]

Unlike other Longhorn builds, it contains a broken timebomb and can be installed on the current date. However, before installation, machine time will still be checked and verified.

WinPE[edit | edit source]

The mouse driver in this build's WinPE does not function on specific hardware configurations or hypervisors, and may require a keyboard to navigate through the installation procedure. This issue appears to be largely related to using a PS/2 mouse, as most ordinary USB mice appear to function properly in setup.

WordPad[edit | edit source]

WordPad does not start, as it will display with Failed to create empty document instead.

Outlook Express[edit | edit source]

Outlook Express does not start due to registry errors and certain dependencies on WinFS.

Themes[edit | edit source]

The Windows Classic theme does not function due to a broken Windows Classic.theme file.

Explorer[edit | edit source]

Windows Explorer is more prone to crashing than in previous builds, especially when shutting down Windows.
CD and DVD drives behave like local disks.
- As a result of this, the system continously throws out notifications about low disk space.
Help and Support crashes Explorer.
Explorer will crash after adding the display tile in sidebar and won't launch again. A workaround is to create a new account via cmd.
When the Aero taskbar and sidebar are enabled, the Taskbar erroneously uses the Sidebar background.

Control Panel[edit | edit source]

Hardware and Devices folder does not open.
By default, the Phone and Modem Options Control Panel applet name is empty.
Computer Management displays script errors due to missing registry entries.

Graphics[edit | edit source]

On some computers, the system will bugcheck with code 0x000000B4 after installing the video driver. To fix this, enable VGA mode in the startup options.

Windows Product Activation[edit | edit source]

Windows Product Activation is missing.

Safe mode[edit | edit source]

The Safe mode is completely broken and results in a bugcheck with code 0x0000007B. This is because the Safeboot key, located in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control is largely incomplete and missing a lot of entries. Restoring the key from an earlier build with working safe mode allows this build to boot properly, but the video driver will not initialize properly. As a result, the operating system will freeze as it transitions into graphical mode, so Safe Mode is currently not known to work on these pre-reset Longhorn componentized builds.