How to solve the error code 0x800F081F: SQL Server 2017 installation failed

There are several possible solutions to this error code:

1. Install .NET Framework 3.5: This error code can occur if the .NET Framework 3.5 is not installed on your system. You can install it by going to Control Panel > Programs and Features > Turn Windows features on or off > .NET Framework 3.5 (includes .NET 2.0 and 3.0).
2. Disable antivirus software: Sometimes, antivirus software can interfere with the installation process. Try disabling your antivirus software temporarily and then try installing SQL Server 2017 again.
3. Use the installation media: If you are installing SQL Server 2017 from a downloaded file, try using the installation media instead. This can help avoid any issues with the downloaded file.
4. Check system requirements: Make sure your system meets the minimum system requirements for SQL Server 2017. You can find the system requirements on the Microsoft website.
5. Run the installation as an administrator: Right-click on the installation file and select "Run as administrator". This can help avoid any permission issues that may be causing the error code.
6. Check the installation log: The installation log can provide more information about the error. You can find the installation log in the %ProgramFiles%\Microsoft SQL Server\140\Setup Bootstrap\Log folder. Look for any error messages or warnings and try to resolve them.