Hi TSmith,
Thank you for reaching out.
The error shown when enabling .NET Framework 3.5 usually occurs when Windows is unable to access or start the system components required to install optional features. This can be related to service availability, system policy settings, or the local Windows component store, even if other updates appear to work normally.
Here is a verified list of the troubleshooting steps that you can try in this situation:
1, Verify required Windows services
- Press Win + R, type
services.msc - Ensure the following are not disabled:
- Windows Modules Installer
- Windows Update
- Background Intelligent Transfer Service (BITS)
- Restart the PC and try installing the feature again
2, Install using Windows installation media
- Download a Windows 10 ISO using the Media Creation Tool
- Mount the ISO (double‑click it)
- Open Command Prompt as administrator
- Run:
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:X:\sources\sxs /LimitAccess(Replace X with the mounted ISO drive letter)
3, Check local policy settings
- Press Win + R, type
gpedit.msc - Navigate to: Computer Configuration > Administrative Templates > System
- Open Specify settings for optional component installation and component repair
- Set it to Enabled, apply changes, and restart
4, Repair system files
- Open Command Prompt as administrator
- Run:
DISM /Online /Cleanup-Image /RestoreHealth - Then run:
sfc /scannow - Restart once complete
If the feature still cannot be installed after these steps, this typically indicates deeper component corruption. In that case, an in‑place repair install of Windows 10 is the recommended approach, as it refreshes system components while keeping apps and files intact.
Let me know if you need further assistance, feel free to ask me by clicking "Add Comment" or "Add Answer" if you cannot add comment so your response will be visible. Thanks for your effort.
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