How to resolve error code 0x800f0818: Feature installation failure in Windows Server 2012 R2

Here are several methods to fix error code 0x800f0818:

1. Update your system: Ensure your Windows Server 2012 R2 has the latest updates. Navigate to Settings > Update & Security > Windows Update and select Check for updates.
2. Run the DISM tool: Launch Command Prompt as an administrator and enter the command: DISM /Online /Cleanup-Image /RestoreHealth. This scans and repairs any corrupted files on your system.
3. Execute the System File Checker tool: Open Command Prompt as an administrator and type: sfc /scannow. This will detect and repair any corrupted system files.
4. Temporarily disable antivirus software: Antivirus programs can sometimes block feature installations. Temporarily disable your antivirus and retry the installation.
5. Use the Windows Server installation media: If the previous steps don't work, use the installation media. Insert it and run setup.exe. Choose to upgrade your current installation and follow the prompts to finish.