Many users fear that installing an older framework introduces security holes. Microsoft has addressed this:
Best practice: Download your offline source from a trusted Windows 10 ISO, then run DISM. Never use "activator" tools or repacked EXEs.
Right-click the Start button > System. Ensure "System type" says 64-bit operating system, x64-based processor. Net Framework 3.5 Offline Installer Windows 10 64 Bit
Once you see "The operation completed successfully", restart your computer.
Copy the sxs folder from the Windows ISO to a local drive (e.g., C:\dotnet35\sxs) and use: Many users fear that installing an older framework
Dism /online /enable-feature /featurename:NetFX3 /All /Source:C:\dotnet35 /LimitAccess
This way you always have an offline installer ready for future use.
Even with an offline installer, errors can occur. Here is how to resolve them. Best practice: Download your offline source from a
For advanced users who prefer PowerShell over CMD.
Enable-WindowsOptionalFeature -Online -FeatureName "NetFx3" -All -LimitAccess -Source "C:\dotnet35"
Press Y to restart. This is essentially the PowerShell wrapper around DISM.
Press Win + R, type optionalfeatures, press Enter.
Look for .NET Framework 3.5 (includes .NET 2.0 and 3.0) – the checkbox should be filled (not empty).