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Error: 0x800f081f The source files could not be found. .net framework 3.5 install error

Question

Wednesday, May 15, 2019 1:03 PM

Hi all

I recently had an issue installing .net framework 3.5. I was unable to add it via Programs and Features and none of the suggestions that i saw worked.

After searching forever and trying lots of different things, i stumbled across this reply in a thread that helped me solve the issue. I'm not sure if it is easily accessible where it is so i am posting it here.

The key bit of information (for me at least) was to use an ISO of Windows 10 that matched my current install- version wise. Using a 1709 ISO with my 1803 install caused my attempts to fail. Using like for like resolved the issue.

"

How to fix.

Download the Windows 10 1809 .iso file using the Microsoft media creation tool

https://www.microsoft.com/en-gb/software-download/windows10

Sign in as admin, run that tool, create media for another PC, download iso.

Once you have the .iso mount the iso (double click on it)

Open the command prompt as admin

Run this command

Dism /online /enable-feature /featurename:NetFx3 /All /Source:d:\sources\sxs /LimitAccess

(d:\sources\sxs = use whatever the drive letter for the mounted .iso is)

This should work.

You MUST MUST MUST use the .iso for the version of Windows you are using... Microsoft checks. Version mismatch between the .iso and your PC and it will fail with some bogus error message and you will spend 3 days pulling your hair out and yelling at people on the internet trying to get a core feature of Windows working because Microsoft wants to play .net version Nazi.


-RW / Redwizzard001 

All replies (4)

Wednesday, May 15, 2019 2:38 PM âś…Answered

Hello,

Thanks for sharing your experience. I hope the solution will help others with same issue.

Regards.

Microsoft MVP (Windows and Devices for IT)

Windows Insider MVP

Windows Help & Support [www.kapilarya.com]


Wednesday, May 15, 2019 2:45 PM

are you sure the system is not using a WSUS server?
I never had problems enabling .NET 3.5 unless the system was in a domain.


Thursday, May 16, 2019 2:20 AM

Hi,

 

Thanks for what you have done for this case.

 

I learn more from your reply, and I believe partners who may visit this thread in the future will benefit from your sharing.

Please remember to mark the replies as answers if they help.
If you have feedback for TechNet Subscriber Support, contact [email protected].


Wednesday, September 25, 2019 5:42 PM

Thank you for this great solution! It was in fact the build of recovery disk I was using. I created a new .iso of the current system then was able to install Framework 3.5 from a bootable USB.