How to fix error code 0x80070003: Windows cannot install required files in Windows 8.1

Here are various methods to fix error code 0x80070003 in Windows 8.1:

1. Run the Windows Update Troubleshooter: Navigate to Control Panel > Troubleshooting > System and Security > Windows Update > Run the troubleshooter.
2. Delete the Software Distribution Folder: Go to C:\Windows\SoftwareDistribution and remove all contents. Restart your computer and attempt the update installation again.
3. Disable your antivirus software: Temporarily turn off your antivirus software as it may hinder the installation process, then try installing the updates again.
4. Check your hard drive for errors: Navigate to This PC > Right-click the desired drive > Properties > Tools > Check. This will scan and repair any detected errors on your hard drive.
5. Reset Windows Update Components: Open Command Prompt as an administrator and enter the following commands sequentially:

    net stop wuauserv
    net stop cryptSvc
    net stop bits
    net stop msiserver
    ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
    ren C:\Windows\System32\catroot2 catroot2.old
    net start wuauserv
    net start cryptSvc
    net start bits
    net start msiserver 

6. Perform a System Restore: If the above solutions do not work, try restoring your system to an earlier point in time when it was functioning correctly.

Note: Ensure you have a backup of all important files and data before attempting any of these methods.