Install .NET Framework 3.5 Features on Windows Server 2012R2

Prepare the .NET Framework 3.5 installation package

1. ​​​​​​​​​​Installation package download address: Download .NET Framework | Free official download (microsoft.com) 
2. Strips .NET Framework 3.5 source files from Windows Server IOS system files.
   1. ​​​​​​​​Take Windows Server 2019 as an example: Click the ISO file to mount.
   2. After loading, open the ISO and open the sources folder.
   3. The folder sxs is the .NETFramework 3.5 source file, and the entire folder needs to be copied for installation.

Install .NET Framework 3.5 offline

1. Open Server Manager and click on "Add roles and features".
2. A wizard window pops up, click "Next".
3. The default "Role-based or feature-based installation" role-based or feature-based installation is used for local installation, click "Next".
4. Select the installed server and click "Next".
5. This page is Server Roles, click "Next".
6. This page is Features, select [.NET Framework 3.5 Features], click ""Next.
7. Click "Specify an alternate source path" to specify the source path.
8. Fill in the path of the offline installation package in Path, and click "Next".
9. Click "Install" to start the installation.
10. Wait for the progress bar and close when the installation is complete.
11. After the installation is complete, you can see it in Features. ​​​​​​​​