How to Fix .NET Framework 3.5 Error 0x800F080C

When you install the .NET Framework 3.5 using DISM in Windows 10 or 11, you may encounter error 0x800F080C. The full error message is below:

Error: 0x800f080c

Feature name NetFX3 is unknown.
A Windows feature name was not recognized.
Use the /Get-Features option to find the name of the feature in the image and try the command again.

Also, when you open OptionalFeatures.exe, the .NET Framework 3.5 entry may be missing.

The above error occurs if the .NET Framework 3.5 package has been removed.

Resolution

Download the Windows 10 or 11 ISO and double-click it to mount it to a drive letter – e.g., G:\.

The “Sources\Sxs” folder in the ISO contains the CAB file (“microsoft-windows-netfx3-ondemand-package~31bf3856ad364e35~amd64~~.cab“) needed to install .NET Framework 3.5.

Open an admin Command Prompt window and run the following command:

DISM /Online /Add-Package /PackagePath:G:\Sources\SxS\microsoft-windows-netfx3-ondemand-package~31bf3856ad364e35~amd64~~.cab

The above command should add the .NET Framework 3.5 package to the computer.

Once done, run the following command to install .NET Framework 3.5.

DISM /Online /Enable-Feature /FeatureName:NetFX3 /All /Source:G:\sources\sxs /LimitAccess

The above examples assume the ISO drive letter is G:. Make sure you use the correct drive letter for your computer.