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Windows 8–can’t install .Net Framework 3.5 (0x800F0906, 0x800F081F)

I’d recently put Windows 8 on a test machine at work and started installing what software I needed. Pretty quickly I found I needed to install .Net Framework 3.5 which is now a ‘Feature’ instead of a separate download.

Switching this on prompted me to download files from Windows Update.

That seemed to go OK for a while.

Unfortunately, after a few minutes, it failed.

Error code 0x800F0906 leads you to troubleshooting articles such as:

.NET Framework 3.5 installation error: 0x800F0906, 0x800F081F, 0x800F0907

“This error code occurs because the computer cannot download the required files from Windows Update.”

  1. First suggestion is to check Windows Update is actually accessible. Start with the easy ones Smile
  2. Getting a little bit trickier, second suggestion is to make sure there isn’t a Group Policy in place preventing the install process from contacting Windows Update.
  3. Then you get your hands dirty with DISM.EXE command line instructions.
Deployment Image Servicing and Management tool

Version: 6.2.9200.16384


Image Version: 6.2.9200.16384


Enabling feature(s)

[===========================65.9%======                    ]


Error: 0x800f081f


The source files could not be found.

Use the "Source" option to specify the location of the files that are required t

o restore the feature. For more information on specifying a source location, see


The DISM log file can be found at C:\Windows\Logs\DISM\dism.log

So now I have a new error code – 0x800F081F – to muddy the water with.

Checking the DISM.LOG file

2014-09-29 14:07:15, Info                  
DISM   DISM Package Manager: PID=2296 TID=1256  Error in operation: source for package or file not found, ResolveSource() unsuccessful. (CBS HRESULT=0x800f081f) - CCbsConUIHandler::Error

2014-09-29 14:07:15, Error                
DISM   DISM Package Manager: PID=2296 TID=4732 Failed finalizing changes. - CDISMPackageManager::Internal_Finalize(hr:0x800f081f)

2014-09-29 14:07:15, Error                
DISM   DISM Package Manager: PID=2296 TID=4732 The source files could not be found; their location must be specified using the /source option to restore the feature. – GetCbsErrorMsg

Not really helpful as it doesn’t explain what’s missing. Now I’m happy with my DISM command:

Dism /online /enable-feature /featurename:NetFx3 /All


so it must be that the files are missing from the install files, which seems unlikely.

Looking for help on the new error code, I found:

Windows Update error 0x800F081F

The recommended DISM.EXE commands to clean up the Component Store made no difference:

dism.exe /online /cleanup-image /scanhealth
dism.exe /online /cleanup-image /restorehealth

I then moved on to Joseph Conway’s Technet blog: 

How to troubleshoot error 0x800F081F when installing roles and features

  1. Download the ISO again – couldn’t complete this one easily. Could fill a blog just on how difficult it is to get access to install software at work…
  2. Clean up the Component Store – already tried
  3. Disable any access to WSUS – also already tried
  4. Update your source media – this sounded promising…

How to update local source media to add roles and features

Sadly, I couldn’t get this to work and gave up trying after a while.

Going back to basics, my next stop was CBS.LOG as that’s where the “Component-Based Servicing” work is recorded.

2014-09-29 14:18:47, Info                 

CBS    Calling client to resolve source, cannot find file 'amd64_microsoft-windows-wpfcorecomp.resources_31bf3856ad364e35_6.2.9200.21161_en-us_0b79bec03324a82a\PresentationHostDLL.dll.mui'

2014-09-29 14:18:47, Info                 

CBS    Exec: Not able to pre-stage package: Microsoft-Windows-IIS-WebServer-AddOn-Package~31bf3856ad364e35~amd64~en-US~6.2.9200.16384, file: PresentationHostDLL.dll.mui, source: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-wpfcorecomp.resources_31bf3856ad364e35_6.2.9200.21161_en-us_0b79bec03324a82a\PresentationHostDLL.dll.mui

Looking in the \sources\sxs folder, I can only see sub-folders for

and so on but not for the missing folders.

Which is when I noticed that the folders have a build number of 6.2.9200.16384 but the missing folder has a build number of 6.2.9200.21161.

Searching online for the build number quickly found problems with a bunch of Windows Update fixes.

.NET Framework 3.5 0x800F0906 then 0x800f081f

Just uninstall updates KB2966826 and KB2966828 and it will help you.

Looking in the list of installed updates, I found I had KB2966827 present:

MS14-046: Description of the security update for the .NET Framework 3.5 on Windows 8 and Windows Server 2012: August 12, 2014

Now why do I have a .NET Framework 3.5 hotfix installed on a machine that hasn’t yet had .NET Framework 3.5 installed?!

The presence of the hotfix meant the installation was always expecting to find newer files than came with the Windows 8 source files.

As soon as I uninstalled the hotfix, I could add the .NET Framework 3.5 feature and start using my applications.

This article is part of the GWB Archives. Original Author: John Breakwell

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