If the online and offline installation of .NET Framework on Windows 11/10 computer fails with error 0x800f081F, the this post will help you fix the issue.

2] Enable .NET Framework from Windows features The issue mentioned will occur if .NET Framework is disabled under Windows features. To solve the problem, you will have to enable the option.

This web page contains information about the Add or Remove Programs control panel entry - Microsoft .NET Framework 1.1 Hotfix (KB925168). More information can be found by visiting this search result.