If you go to "Turn Windows features on or off" and check ".NET Framework 3.5 (includes 2.0 and 3.0)," Windows will tell you it needs to download files. Here is why that frequently fails:
The solution? The Offline Installer. Instead of pulling bits from Microsoft's server during installation, you provide the source files locally. net framework 3.5 sp1 offline installer
Warning: Do not download installers from third-party "DLL download" websites. Many contain viruses or modified binaries. Always get the file from Microsoft directly. If you go to "Turn Windows features on or off" and check "
.NET 3.5 SP1 is still supported by Microsoft as part of the lifecycle for Windows Server and Windows 10/11. Security updates for .NET 3.5 SP1 are delivered through Windows Update monthly (Patch Tuesday). Ensure you have the latest updates after installation. The solution
Latest update as of 2024: August 2024 Security and Quality Rollup (KB5042099 for .NET 3.5).