Windows 10 (and also 8.1) doesn’t come with DotNet Framework 3.5/2.0 preinstalled. Running the .Net Framework 3.5 installer (dotnetfx35.exe) that used to work on Windows 7/Vista likewise doesn’t work on Windows 10 instead it prompts one to install it via Windows Update.
Ironically Microsoft includes the install packages in the Windows 10 ISO for those that need to install the framework on demand. It’s these packages that I’ve been using since Windows 8.1 to install the framework on my machine offline.
So it came as a surprise to me recently when I run into an error after trying to install the framework on a fresh install of Windows 10 build 1809. To me, nothing had changed. I was using the same command that had worked on past installations:
Dism /online /enable-feature /featurename:NetFX3 /All /Source:V:\source\sxs /LimitAccess
Instead every time I run the command I was greeted by the error: 0x800f081f. Apparently the source files could not be found yet the package was available in the mounted location.
So I tried installing the package from an older build of Windows (10240) and a Windows 8.1 ISO but the same error came up. I even tried using different cases and arrangements for the command but the error persisted.
Searching online, the error itself seemed prevalent but was not necessarily occurring only during the offline installation. It’s only after this that I decided to take a closer look at my command and realized the source of the problem.
Turns out I was using an incorrect path. All this time I had been specifying \source\sxs as the path instead of \sources\sxs. The command should’ve been (where X is the mount point):
Dism /online /enable-feature /featurename:NetFX3 /All /Source:X:\sources\sxs /LimitAccess
Dism /online /enable-feature /featurename:NetFX3 /All /LimitAccess /sources:X:\sources\sxs
Using upper or lower case had no effect in my case contrary to what I’ve seen mentioned in a certain forum. They all worked perfectly. Just make sure the path is correct.