Symptom 1You experience slow interactive logons and RDP logons to a computer that is running Windows 8.1, Windows RT 8.1, or Windows Server 2012 R2.
The explorer.exe process reads thousands of Windows Push Notification Platform (WPN) and Windows Notification Facility (WNF) values from the following registry subkey during the user logon:
Also, the logon may consume high CPU usage for a long period of time during using logon.
Symptom 2You may receive an error message that resembles the following when you use an app that uses the BackgroundDownloader class:
After you encounter this error, restarting the app or the system does not resolve the issue. At the same time, other apps (such as the Windows Store app) that use the BackgroundDownloader class may also experience the same error.
Leaked WNF registrations cause the Explorer.exe process to read many registry values from the notification registry subkey when the system initializes the process. Lots of WNF registrations can delay user logon and increase CPU usage.
Additionally, the 0x800705AA error may occur when the BackgroundDownloader class tries to allocate a WNF state name and fails.
How to obtain this update
This update improves performance when system initializes the explorer.exe process.
Method 1: Windows Update (recommended)This update is provided as an Optional update on Windows Update. For more information on how to run Windows Update, see How to get an update through Windows Update.
Method 2: Microsoft Download CenterThe following files are available for download from the Microsoft Download Center:
|All supported x86-based versions of Windows 8.1||Download the package now.|
|All supported x64-based versions of Windows 8.1||Download the package now.|
|All supported x64-based versions of Windows Server 2012 R2||Download the package now.|
For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:
Update detail information
PrerequisitesTo install this update, you must have April 2014, update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 (2919355) installed in Windows 8.1 or Windows Server 2012 R2.
Note If update 2919355 is not preinstalled, the installation of update 3063843 may fail with "The update is not applicable to your computer" error.
Registry informationTo apply this update, you do not have to make any changes to the registry.
Restart requirementYou may have to restart the computer after you apply this update.
Update replacement informationThis update does not replace a previously released update.
Additional steps for configurationWe recommend that you install this update through Windows Update as doing this installs the fix and removes the leaked registrations.
If you download the package directly from the Microsoft Download Center, you have to manually extract the wnfcleanup tool from the MSU package. To extract the cleanup tool from the MSU package by opening an elevated command prompt by using Run as administrator, run the following commands in order:
Copy %userprofile%\Downloads\Windows8.1-KB3063843-* c:\wnfcleanup
expand Windows8.1-KB3063843-*.msu -F:wnfcleanup.exe .\
Note The full stop (.\) is important as it says to extract the EXE to the current location where the MSU is.
Then, create a scheduled task to clean up the existing registry entries by running the wnfcleanup.exe tool as SYSTEM.
The following commands should be run in an elevated command prompt to create a scheduled task. The task executes a command as SYSTEM to run the cleanup tool. Then, the task is deleted.
SCHTASKS /create /f /SC hourly /TN Wnfcleanup /TR "cmd /c c:\wnfcleanup\wnfcleanup.exe -delete" /RU "SYSTEM"
SCHTASKS /run /I /TN "Wnfcleanup"
Now leave the system for several minutes so that the task can execute and be completed. You can check the status of the Wnfcleanup task to see whether it has completed and returned to the "ready" state by running the following commands:
SCHTASKS /QUERY /V | findstr /I "wnfcleanup" > .\cleanup.txt
As soon as it is completed, delete the task:
SCHTASKS /delete /TN "Wnfcleanup" /f
Note The wnfcleanup tool must be run in the SYSTEM security context. This is why the task scheduler is used. Or, you could run it by using a tool such as PsExec.
About Windows Push Notification PlatformWindows Push Notification Platform is a component that exposes a notification sink to notify of notification changes, and an API to communicate how to interact with the notifications.
About Windows Notification FacilityWindows Notification Facility is an infrastructure for secured publish-subscribe messaging among kernel components, system services, and user-space applications.
When you try to register for a notification to a new state name, there will be a potential access to the registry. All state name definitions are stored in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Notifications.