//free\\ — Windows8.1-kb2999226-x64

Without KB2999226, those applications would immediately fail on launch with:

If you maintain legacy Windows 8.1 systems: windows8.1-kb2999226-x64

Windows 8.1 reached end of life on . No more security updates. But many legacy systems (industrial control, medical devices, air-gapped networks) still run 8.1. KB2919355: The Windows 8

If the update fails citing "Side-by-Side" configuration errors, it usually means the prerequisite (KB2919355) is partially installed or corrupted. In this case, downloading the Windows 8.1 "Update 1" rollup and installing it offline is usually the most reliable fix. not a typical bug fix.

Before installing KB2999226, your system must have the following "servicing stack" updates, or the installation may fail with an "Update is not applicable" error: A prerequisite update for Windows 8.1. KB2919355: The Windows 8.1 Update (April 2014). 3. How to Install

windows8.1-kb2999226-x64 is a , not a typical bug fix. It bridged the gap between Windows 8.1 and the modern Windows 10 app ecosystem.