Hi SHAFEEQUE,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
The error code 0x80072F8F you're encountering during the installation of .NET Framework 3.5 on Windows 11 is often related to date and time issues on your PC, or problems with the Windows Update service.
Unfortunately, .NET issue is not supported on the Microsoft Answers forum. It is more suitable for publishing on Microsoft Learn (English only), you can click on "Ask a question", there are experts who can provide more professional solutions in that place.
Here is a link: .NET - Microsoft Q&A to the forum where you can raise specific scenarios and share your idea to help solve the problem.
Windows Update Service is a critical component in ensuring your operating system remains up to date. If your system cannot connect to the update service, you may not be able to get the latest security patches, feature updates, and fixes. Here are some possible solutions, you can try one of them:
Check whether the service is enabled:
- Press
WIN + Rkeys, then enterservices.mscin Run and hit enter. - Find and double-click to open the
Windows Update,Cryptographic Services,Background Intelligent Transfer ServiceandWindows Installerservices in the services interface. - Make sure the startup type for these services is set to Automatic, then click Apply, Start and OK.
More Methods: Troubleshoot problems updating Windows - Microsoft Support
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn - MSFT | Microsoft Community Support Specialist