Resolving Error Code 0x800f0929 for .NET Framework 3.5 on Windows Server 2012

To troubleshoot error code 0x800f0929 while installing .NET Framework 3.5 on Windows Server 2012, follow these steps:

1. Check existing installation: Navigate to Control Panel > Programs and Features > Turn Windows features on or off. Verify whether .NET Framework 3.5 is already installed and functioning properly.
2. Utilize DISM command: Launch Command Prompt as an administrator and enter: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs (replace 'D:' with the correct drive letter of your server’s installation media) to install from the media.
3. Run Windows Update Troubleshooter: Access this tool via Control Panel > Troubleshooting > System and Security > Fix problems with Windows Update, and follow the prompts to identify and resolve update issues.
4. Manually install .NET Framework 3.5: Visit the Microsoft Download Center, download the .NET Framework 3.5 installer, and follow the on-screen instructions for installation.
5. Check for Windows updates: Go to Control Panel > Windows Update, perform a check for updates, and install any available updates that pertain to .NET Framework or the Windows Server 2012 system.