Windows 8 build 7850

Windows 8 build 7850 is a build of Windows 8. This build was originally leaked as an x86 Enterprise SKU version on 12 April 2011, then on 17 January 2015, an x64 version was leaked of this build along with more SKUs for both the x86 and x64 architectures.

Being early in development, many areas still say Windows 7 and the kernel is still 6.1 (much like builds 7700 and 7746). The default background image of this build is a bluish gradient with a green tint at the lower right and a message at the top telling not to leak this build ("shhh... let's not leak our hard work").

It was the first build to drop support for booting from a FAT32 partition, as booting from a FAT32 partition will display a BSOD instead.

But it is the first to support booting from the exFAT partition. From a certain perspective, Microsoft intends to let exFAT further replace FAT32.

Redpill
The 2020-03-02 build of Redlock unlocks various features in this build. It's the earliest leaked build to implement Redpill.

The Start screen in this build is rather primitive, having only one view featuring every installed application with a tile. It also includes a button to bring up an early search pane. A very early and non-functional snap UI is seen when you exit from the Start screen. A primitive Charms bar is also implemented and is accessible by pressing WIN+C on your keyboard, but it is non-functional. New folder icons, along with a preview grid, are present in this build when Redpill is enabled. Other features include:


 * Support for 32-bit UEFI boot
 * Support for booting from an exFAT partition
 * 4K Native logical sector boot
 * Hybrid boot
 * Explorer Ribbon UI (icons are all circles)
 * User tile (located at the right of the taskbar)
 * Centered title bar text
 * Explorer up button
 * Built-in PDF Reader (basic)
 * Modern Task Manager (partially broken)
 * Webcam Application (full screen)
 * Built-in virtual optical drive (double-click the ISO file to directly mount the image)
 * Auto colorization of themes
 * ApplicationExplorer shell location (Applications.{4234d49b-0245-4df3-b780-3893943456e1}) - tabs include "Tile state" and "Host environment". This is where the Start screen app list is stored, even up to 8.1.
 * Aero Lite (basic)
 * Early beta of IE9
 * Built-in, working USB xHCI drivers
 * Built-in UASP drivers
 * Certificates and digital signatures that recognize the SHA256 algorithm
 * New Disk Cleanup (diskclean.exe)
 * System reset (sysreset.exe), which has a version build number of 7782
 * Portable Workspace Creator (pwcreator.exe)

PDF Reader
There is a very early version of the Immersive Reader included, accessible by running  with any PDF file as an argument (or without any argument to open a blank page).

Modern Windows Task Manager
A preliminary version of the Modern Windows Task Manager is included as well. It is accessible by running.

Ribbon UI
A Ribbon version of Windows Explorer is included as well. However, most of the icons for it are placeholder circle icons.

Webcam Capture Application
An early version of the webcam capture application is included as well, accessible by running.

Auto Colorization
Create a copy of a theme from, add   to the end of the   section and apply.

Bugs and quirks

 * Windows Classic and the High Contrast themes are broken.
 * Changing the date appears to freeze up the Explorer shell.
 * Using Desktop Gadgets significantly slows the OS down.
 * Upgrade in this build is broken.
 * Some setup strings don't show properly. For example, instead of "Setup is starting" or "Setup will continue after restarting your computer," "Setup is" or "Setup will continue after restarting your" strings will appear.
 * The original 2011 leak of this build is bundled with the Windows 7 RTM pre-installation environment.

Aero
This build appears to have a slightly broken Windows Aero theme, with only the top portion of the window frame using the blur effect, leaving the side borders transparent.

Upgrading to later builds
Newer builds may oddly identify this build as Windows XP when trying to upgrade.