How to resolve the error code 0x800f0831: Unable to install .NET Framework 3.5 on Windows Server 2016

Here are the steps you can follow to resolve error code 0x800f0831 when installing .NET Framework 3.5 on Windows Server 2016:

1. Verify if .NET Framework 3.5 is installed: Open Control Panel, go to Programs and Features, and check for Microsoft .NET Framework 3.5. If it's listed, you don't need to install it again.
2. Utilize the DISM command: Run Command Prompt as an administrator and enter: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs. Substitute 'D:' with your Windows Server 2016 installation media drive letter. This will install .NET Framework 3.5 from the installation media.
3. Use Windows Server 2016 installation media: Insert the installation media and open File Explorer. Navigate to the Sources folder and locate the 'sxs' file. Copy it to your desktop or another location. Open Command Prompt as an administrator and enter: Dism /online /enable-feature /featurename:NetFx3 /All /LimitAccess /Source:C:\sxs. Replace 'C:' with the drive letter of the location where you copied the 'sxs' file.
4. Update Windows: Ensure your Windows Server 2016 is current with all updates. Go to Settings > Update & Security > Windows Update and check for updates. Install any available updates and attempt the .NET Framework 3.5 installation again.
5. Disable antivirus software: Antivirus programs can sometimes block the installation of .NET Framework 3.5. Temporarily disable your antivirus software and try installing .NET Framework 3.5 again.