Since downloading windows10 - I was on windows 7 previously

When opening Windows Live Mail I receive the following message

"An app on your PC needs the following windows feature

.NET Framework 3.5 (includes .NET 2.0 and 3.0)

Download and install this feture

Windows will get the file from windows update and complete the installation

After clicking download I receive

Searching for required files

the

downloading required files

Download fails and the following message appears

The following feature couldn't be installed

.NET Framework 3.5 (includes 2.0 and 3.0)

Windows couldn't find required files to complete the requested changes.  Make sure you're connected to internet and try again

error code 0x800F081F

I am connected to the internet using an efernet cable so cannot understand this error message

Do I need the app

If so how do I get the app

If I do not need this app how do I stop the message appearing when I open windows live mail