Resolving Error 0x800f0928: Installing .NET Framework 3.5 on Windows Server 2012

To troubleshoot error code 0x800f0928 when installing .NET Framework 3.5 in Windows Server 2012, follow these structured steps:

1. Verify installation of .NET Framework 3.5: Open Server Manager, navigate to the 'Add Roles and Features' wizard, and check if .NET Framework 3.5 is installed. If present, consider repairing it.
2. Deploy DISM command: Launch Command Prompt with admin rights and execute: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs (substitute 'D:' with your installation media’s drive letter). This will fetch .NET Framework 3.5 from your media.
3. Utilise Windows Update: Access Windows Update settings, search for updates particularly relevant to .NET Framework, install them, and retry the .NET Framework 3.5 installation.
4. Adjust Group Policy settings: For domains, inspect the Group Policy settings that affect .NET Framework setup. Ensure the 'Specify settings for optional component installation and component repair' policy is enabled, and the WSUS policy allows direct downloads from Windows Update.
5. Examine antivirus interference: Temporary disable any antivirus software as it might block the installation of .NET Framework 3.5. After disabling, attempt the installation again.
6. Inspect Windows Installer service: Confirm that the Windows Installer service is active. Open the Services console, check the service status, and if inactive, start it and proceed with the installation.
7. Check system files: Run the System File Checker (SFC) by opening Command Prompt as administrator and typing: sfc /scannow. This tool will identify and repair any damaged system files.