Member Avatar for professor123

Good day,
I have been trying to enable dotnet 3.5 on my laptop which is running Windows 10.I have tried the following solutions from the internet with no success:

  1. Enable the feature from control panel
  2. Downloaded the DotNetFx35Client and DotNetFx35.exe installs but they are end up trying to download from the internet and they fail
  3. Using the Microsoft-Dot-Net-Framework-35-Offline-Installer but no joy

  4. Using the DISM tool but get this output
    >>Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:C:\sources\sxs
    Deployment Image Servicing and Management tool
    Version: 10.0.10240.16384
    Image Version: 10.0.10240.16384
    Enabling feature(s)
    Error: 0x800f081f
    The source files could not be found.
    Use the "Source" option to specify the location of the files that are required to restore the feature. For more information on specifying a source location, see http://go.microsoft.com/fwlink/?LinkId=243077.

    1. Tried to check if these KBs (KB2966826, KB2966827, KB2966828) are not installed and they were not installed

    Can someone please assist me I seem to have exhausted most internet solutions

    Please assist.

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Dani AI

Generated

As discovered, the usual cause of a failed .NET 3.5 enable is that Windows cannot find the framework payload in the component store. The reliable fix is to point the feature installer (or DISM) at installation media that exactly matches the running Windows build, edition and language — mounting the correct Windows ISO as the source typically resolves the error.

Quick checklist to avoid the common pitfalls:

  • Confirm the exact Windows build and edition (Settings > System > About or run winver) so the media really matches the installed OS.
  • Use installation media from the same build/servicing baseline and language; mismatched ISOs are the most frequent reason the files “cannot be found.”
  • If the source image is compressed (ESD) or packaged differently, mount or extract it so Windows can read the payload files.

If the media is correct but the install still fails, repair the local component store first. Run these from an elevated prompt:

sfc /scannow

DISM /Online /Cleanup-Image /RestoreHealth

Also verify Windows Update services are running and that WSUS/Group Policy is not blocking payload downloads — managed environments often prevent Windows from pulling feature files from Microsoft.

Notes and final tips: many “offline” installers will still attempt to contact Windows Update if the component files are missing; using matching installation media avoids that. For enterprise machines follow corporate update processes; for standalone PCs create or obtain the ISO that exactly matches the current build before retrying. The approach used — mount the correct OS disk and use it as the source — is the most reproducible solution.

Member Avatar for professor123

Ooh dear I finally got it.

I mounted my OS iso (nb: the OS iso must be the same version as the OS running on the machine) as a virtual disk and i run the DISM utility using the above command and it worked like a charm.....

I was using the wrong OS Disk...

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