Windows 10 build 9838 (fbl partner eeap)

Windows 10 build 9838 (fbl_partner_eeap) is a Technical Preview build of Windows 10, which was originally uploaded to BetaArchive on 17 January 2019 in the Japanese language. The x64 English checked/debug compile of this build was later shared on 4 November 2024 along with its server counterpart. This build was originally released to Microsoft partners participating in the Ecosystem Engineering Access Program (EEAP), as indicated by the fbl_partner_eeap branch.
== Editions and keys ==
Edition / SKU Name 	Key
Core 	334NH-RXG76-64THK-C7CKG-D3VPT
Professional 	XHQ8N-C3MCJ-RQXB6-WCHYG-C9WKB
ProfessionalWMC (edition upgrade only)	GBFNG-2X3TC-8R27F-RMKYB-JK7QT
== New features and changes ==
=== User interface ===
The network icon on the taskbar now opens directly in the its respective PC settings applet. This may be a reference that a new network flyout which fits with the new design of Windows 10 was planned. An iteration of the new network flyout can be seen in build 10009, though a placeholder with the "Hello World" text was found in earlier builds. At this point in development though, no visible work has begun yet, as if the user changes it back to open a flyout, the Windows 8.1 flyout will open.
The ability to display toast notifications at the bottom has been added. It can be added by merging the following registry entry:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer]
"DisplayToastAtBottom"=dword:00000001
9838-BottomToast.png|Toast notification on the bottom
=== Applications ===
A DockingController application has been added, which was used as an application for Surface tablets to switch between tablet mode and desktop mode.
Additionally, a reference to Project Spartan (would become Microsoft Edge later on) can be found in this build's start menu, however it points to an invalid location; the main executable and folder do not exist in this build. However, it reveals that the browser would be installed in the folder Microsoft.zSpartan_6.4.9838.0_x64__8wekyb3d8bbwe, and its executable was called Spartan.exe.
File:9838-SpartanRef.png|Project Spartan reference
The Devices Flow application now serves the function of letting the user connect to other devices, which would be moved to the keyboard combination in the RTM build.
File:9838DevicesFlow.png|Devices Flow
In addition to the original Windows Update page in PC Settings, a Windows Update (Threshold) page has also been added, which would become the future Windows Update page in later builds. It can be enabled by merging the following registry key:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate\UX]
"IsMusUxEnabled"=dword:00000001
File:9838SettingsWUTH.png|Main page
File:9838SettingsWUTHS.png|Advanced options page
File:9838-UTSelectUpdates.png|Select updates page
File:9838-UTUpdateHistory.png|View your update history page
File:9838-UTUpdateHistoryMenu.png|Ditto, with menu
A Storage Sense page has also been added on the home page of the PC Settings app, however it currently lacks functionality.
File:9838-StorageSense.png|Storage Sense page
Many development UWP apps has been added exclusively to the debug compile to test various functionality. These UWP apps are all a part of the Windows Communication apps (microsoft.windowscommunicationsapps), which in retail builds includes the Calendar, Mail and People apps.
The list of the debug apps in this build is as follows:
*AddressWell Test App - tests the contact picker
*AddressWellUT - unit test for the contact picker
*Assert - reports assert failures for apps
*AttachmentWellUT - unit test for the "attachment well" - possibly a file picker
*Calendar - the regular Calendar app
*Calendar Provider Test - lets the user perform various actions with the calendar, however crashes when the button to do the action is pressed
*CalendarTest - Calendar app with mock data, doesn't require a sign in, and retains the user's added events
*CalendarUT - unit test for the calendar
*CalPlatUT - unit test for the calendar platform
*CanvasUT - unit tests for the canvas
*CommUT - unit tests for the communication platform
*FontSelectorUT - unit test for the font selector
*FromControlUT - unit test for the from control - possibly the "From" field in an e-mail client
*IC Test - lets the user test how various communications controls react to various data
*JxUT - unit tests for "Jx"
*Mail - the regular Mail app. Doesn't seem to load
*MailTest - Mail app with mock data
*MailUT - unit tests for the Mail app
*MenuArrowKeyHandlerUT - unit test for the menu arrow key handler - some sort of menu
*People - People app with the ability to use mock data
*PeopleUT - unit tests for the People
*Picker Test - lets the user test the contact picker
*PlatformUT - unit tests for the platform
*Protocol Activation Test App - lets the user test launching the People app via various protocols
*SendASmileUT - unit test for Send a Smile - possibly a feedback tool
*ShareAnythingUT - unit test for Share Anything
*ShareTargetTestApp - lets the user test sharing to an app. As it's a share target, content can be shared to this app from another app, where it pops up as a charm and shows information about the shared content
*ShareTargetUT - unit tests for the share target
*Sharing Test - lets the user test sharing to another app
*Skype Test App - lets the user test Skype activation parameters
*SyncUT - unit tests for syncing
*TAEF Tailored Application Host Process - crashes on startup
*TAEF Tailored Managed Application Host Process - crashes on startup
*Test Harness - lets the user test various things relating to communication apps
*TxUT - unit tests for "Tx"
*Windows Live From Control Test App - lets the user test the "From" control
*Windows Live Modern Canvas Test App - crashes on startup
====Gallery====
9838AddressWell Test App.png|AddressWell Test App
9838Calendar Provider Test_b1.png|Calendar Provider Test
9838CalendarTest_b1.png|CalendarTest
9838IC Test_b1.png|IC Test
9838MailTest.png|MailTest
9838People_b1.png|People (splash page)
9838People_0_b1.png|People (main page with mock data)
9838PickerTest.png|Picker Test
9838Protocol Activation Test App_b1.png|Protocol Activation Test App
9838ShareTargetTestApp.png|ShareTargetTestApp
9838sharingtest.png|ShareTargetTestApp being shared to from Sharing Test
9838SharingTest1.png|Sharing Test
9838SkypeTestApp.png|Skype Test App
9838TestHarness.png|Test Harness
9838WindowsLiveFromControlTestApp.png|Windows Live From Control Test App
=====Unit test app=====
The UI is the same between all the unit test apps. Only the unit tests themselves differ.
9838UT1.png|Unit test selection
9838UT2.png|Running unit tests
9838UT3.png|Results page
== Bugs and quirks==
=== User interface ===
Some message boxes in the Japanese version, including the winver and "About Program" dialogs aren't properly resized. As a result, most of the buttons are missing.
When window auto-colorization is enabled, the borders of window thumbnails on the taskbar remain unchanged in color, even when the wallpaper is changed. This problem can be resolved by either manually adjusting the window color via the Control Panel or by performing a restart. 
=== Applications ===
The splash screen of UWP apps may appear glitched out on the debug compile.
== Gallery ==
=== Setup ===
==== Japanese version ====
File:Windows10-6.4.9838pretp-Setup-Lang.png|Language selection
File:Windows10-6.4.9838pretp-Setup-Main.png|Setup
File:Windows10-6.4.9838pretp-Setup-EULA.png|EULA
File:Windows10-6.4.9838pretp-Setup-Copying.png|Copying files
File:Windows10-6.4.9838pretp-Setup-Ready.png|Getting PC ready
File:Windows10-6.4.9838pretp-OOBE.png|OOBE
File:Windows10-6.4.9838pretp-OOBE2.png|First logon animation
=== Interface ===
==== English version ====
File:9838MtcUvc.png|MtcUvc
File:9838MIE.png|Modern Internet Explorer
File:9838PrintDialog.png|Print Dialog
==== Japanese version ====
File:Windows10-6.4.9838-Desktop.png|Desktop
File:Windows10-6.4.9838-About.png|winver
File:Windows10-6.4.9838pretp-LockScreen.png|Lock screen
File:Windows10-6.4.9838pretp-LoginScreen.png|Login screen
File:Windows10-6.4.9838pretp-StartMenu.png|Start menu
File:Windows10-6.4.9838pretp-StartScreen.png|Start screen
File:Windows10-6.4.9838pretp-CharmsBar.png|Charms bar
File:Windows10-6.4.9838pretp-NotificationCenter.png|Notification Center
File:Windows10-6.4.9838pretp-TaskView.png|Task view
File:Windows10-6.4.9838pretp-Settings.png|Settings app
File:Windows10-6.4.9838pretp-IE.png|Internet Explorer 11 (with About dialog)
=== Miscellaneous ===
Win8boot.png|Boot screen
Windows10-6.4.9833-ThumbnailError.png|Incorrect taskbar preview border color
Category:Windows 10 builds