If you are seeing an error code 0x800F081F when you try to install .NET Framework on your Windows computer. Press start, type Run, type services.msc, Scroll to "Windows Update" and right click and select Start if Stopped. Try to update again.
If you are unsure how to manually add 3.5 in W10 follow this guide:
a) Press “Windows Logo” + “R” keys on the keyboard.
b) Type “appwiz.cpl” in the “Run” command box and press “ENTER”.
c) In the “Programs and Features” window, click on the link “Turn Windows features on or off”.
d) Check if the “.NET Framework 3.5 (includes .NET 2.0 and 3.0)” option is available in it.
e) If yes, then enable it and then click on “OK”.
f) Follow the on-screen instructions to complete the installation and restart the computer, if prompted.
