.NET Framework 3.5 runs in a separate runtime environment and does not interfere with newer .NET Core or .NET 5+ versions.
Open PowerShell or CMD and type:
Close the wizard. Do not use the GUI. Always use the DISM command line for offline installation. The GUI often hangs trying to contact Microsoft servers even when an offline source is selected. download net framework 3.5 offline installer windows 11
The solution is to use an – a single, large file (approximately 250 MB) that contains all the necessary CAB files. You can store this on a USB drive, network share, or external HDD and use it forever without re-downloading.
For more information about the .NET Framework and troubleshooting tips, check out the following resources: Always use the DISM command line for offline installation
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By creating your own using the DISM tool and a Windows 11 ISO, you become immune to internet outages, slow servers, and corporate WSUS blocks. You can store this on a USB drive,
It runs with newer .NET versions (4.x, 5+). Installing it will not break modern apps.