DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:C:\temp

Administrators can deploy .NET Framework 3.5 via Group Policy Objects (GPO):

These errors typically mean Windows cannot find the source files or is being blocked by a local network policy.

Click . Windows will pull the necessary installation files from Windows Update. Troubleshooting Common Installation Errors

Right-click dotnetfx35.exe and select to begin the installation.

He grabbed a USB stick—a battered 16GB SanDisk that had survived three jobs and one accidental trip through the washing machine—and plugged it into his own gaming PC. He navigated to the Microsoft Volume Licensing Service Center, then to the Windows 10 ISO download page. He didn’t need the whole ISO, just one folder.

reg query "HKLM\SOFTWARE\Microsoft\Net Framework Setup\NDP\v3.5" /v Version