Get-WindowsOptionalFeature -Online -FeatureName NetFX3 or check Control Panel → Programs → Turn Windows features on/off → should be checked. Common Errors & Fixes | Error | Solution | |--------|----------| | 0x800f081f – Source not found | Ensure ISO/sxs path is correct | | 0x800f0906 – Cannot download | Use /LimitAccess and valid source | | 0x800f0950 – Incompatible version | Use Windows ISO matching target OS build | | dotnetfx35.exe fails on Win10/11 | Ignore it – use DISM + ISO method | Summary Table – Which Method to Use | Windows Version | Recommended Offline Method | |----------------|-----------------------------| | Windows 7 / 8 / 8.1 | dotnetfx35.exe (official redist) | | Windows 10 / 11 | DISM + Windows ISO sxs folder | | Windows Server 2016/2019/2022 | DISM + ISO or network share | | Air-gapped / multiple PCs | Copy sxs folder to network share or USB |