.NET Framework is a piece of software, developed by Microsoft, which provides a number of core features to the Windows platform.
Any applications developed in “.NET” have the benefit of a range of different upgrades, features and libraries which are not available without the package.
The tradeoff is that in order to get the applications working on your system, you need to have.NET installed and running. This error tends to show when you try and install the 3.5 version of it.
The fix – according to Microsoft – is to actually perform a core update of the Windows OS from an ISO file. This isn't a major issue but there are also a number of other steps you can take too.
Cause
The error typically shows with the following message:
Error: 0x800f0906
The source files could not be downloaded.
0x800F0906 – CBS_E_DOWNLOAD_FAILURE
Error code: 0x800F0906
The cause of the problem is that the “Windows Image” is corrupt.
This means that certain files, settings and options within the Windows OS will not be working properly, leading the error to appear.
The solution is a blend of updating Windows and ensuring that there are no core errors with its settings etc.
Solution
1. SFC/DISM
The “SFC” (System File Checker) + “DISM” (Deployment Image Servicing and Management) applications are standard elements of the Windows ecosystem.
Whilst they are highly effective, they're not that good at fixing the 0x800f0906 error unfortunately.
Nonetheless, they are the least intrusive way to work towards a solution, and thus need to at least be attempted before doing any more heavy-lifting.
- Press “Windows” + “S” keys on keyboard
- This will bring up the “search” box, into which you should type “CMD”
- From the list that appears, right-click “Command Prompt” with your mouse and choose “Run as Administrator”
When it loads, type the following:
- “SFC /scannow”
- This will run for some time – after which it will show the “results” of the progress (it should be okay)
- Once complete, type “DISM /Online /Cleanup-Image /RestoreHealth”
- This will perform another scan – let it run and then in the end it should showcase the results for you
- Restart your PC
The point of this is to clean up any of the “system” files that may be present on your system.
Windows has a large number of “system files” which are required to keep it running as smoothly as possible. Both SFC + DISM are able to fix the majority of these problems, but not all.
It's highly likely that the 0x800f0906 error will not be resolved with this step alone.
2. Internet Connectivity
The next step is to check Internet connectivity.
This might sound trivial, but it's often the case that a large number of systems will have specific issues with the way their Internet is connected.
If you want to make sure that your computer is able to download the appropriate files / updates, you need to ensure that the Internet is fully working:
- Load up your preferred web browser
- Try connecting to the “Windows Update” website
If the connection works in a browser, you'll need to try it from CMD:
- Press “Windows” + “S” keys on your keyboard
- In the “search” box that appears, type “CMD”
- Right-click the listings and select “Run As Administrator”
- Type: “ping update. Microsoft. com” (without spaces)
- If the ping is successful, it should be okay
3. Group Policy Settings
If the above does not work, you'll need to ensure your user account has the correct permissions to actually download various updates (such as.NET).
- Press “Windows” + “S” keys on your keyboard
- In the “Search” box, type “Group Policy” and click on the “Edit Group Policy” listing which appears
In the applet which loads, do the following:
- Select “Computer Configuration” from the left sidebar
- Select “Administrative Templates” + “Systems”
- From the list that appears, select “Specify settings for optional component installation and component repair”
- Select “Enabled” from the left settings menu
- Click “OK”
- Try installing.NET again
If this does not work, it is likely that the “source” for the installation is corrupt or damaged. To solve this, we can use the Windows installation medium.
4. Windows Installation Medium
Lastly, you want to try using the Windows Installation Medium to create a set of new files which any.NET installation is able to use.
This is a common practice, and can be done using the following steps:
- Search for “Windows Media Creation Tool”
- Click on the first Microsoft site that appears
- Click the “Download Tool Now” button
- Save the file to your hard drive & load it up
- Select “Create ISO”
- Follow the steps to create an ISO (which you should then double-click to “mount”)
Once the ISO is mounted, you will then be able to reference its files as required.
To do this effectively, you'll be able to use the third step – except, this time you'll be able to manage the “source” to include the installation files that your system may need.
You can do this using the following:
- Follow the “Group Policy Settings” steps in step 3
- Before clicking “OK”, input “[[ISO drive path]]/sources/sxs” into the “Alternate source file path” box
- Run “gpupdate /force”
- Add the.NET feature
- Restart your PC
If the above do not work, it suggests you have a deeper issue within Windows.
To resolve this, you'll either need to talk to someone with direct access to your system, or people who are able to categorize the error for you. Obviously, an Internet article cannot do that.
