The "6.1" in the filename refers to the Windows NT version for . The KB958488 update serves as a critical component for the .NET Framework 3.5.1, which is often pre-installed as a feature in Windows 7 but requires specific updates to remain compatible with newer applications. It is frequently encountered when users attempt to install .NET Framework 4 , as the installer may attempt to call this specific MSU file to update existing framework components before proceeding. Common Installation Issues
: This indicates the update is built for 64-bit processors, which became the standard for performance-heavy computing during the Windows 7 era. Download Windows6.1-kb958-488-v6001-x64.msu