Windows 11 KB5121003 Security Update Triggers Game Crashes, Microsoft Says

A new security update for Windows 11 is causing stability issues for some players, with certain games reporting crashes, freezes, or even unexpected system restarts after installation. Microsoft has confirmed the problem and is investigating the underlying cause.

What Windows 11 update is affected

The issue is tied to the August Windows 11 security update KB5121003. After installing it on affected systems, players have reported that titles such as Arc Raiders, The Finals, and Marvel Tōkon: Fighting Souls can crash or freeze. In some cases, PCs may also restart unexpectedly.

Why it happens: an older low-level driver

Microsoft points to an older third-party driver named “inpoutx64.sys” as the main culprit. The driver is commonly associated with components and software used for RGB lighting, but it’s not limited to lighting functions. It can also be used by tools for hardware monitoring, fan control, or other tuning features. Because the driver operates at a low system level, it can conflict with changes introduced in Windows 11.

Systems most likely to be affected are those where older software continues to install or keep the driver in place. Embark—the studio behind Arc Raiders and The Finals—had previously suggested a relationship between the crash behavior and “inpoutx64.sys,” referencing the connection via Discord.

Temporary workaround: disable the driver

Microsoft has provided a temporary workaround for affected users: disable the inpoutx64 driver through the Windows Registry. This may prevent the crashes, but it can also break or reduce functionality in RGB software and any connected hardware that depends on that driver.

If you choose to apply the workaround, Microsoft specifically warns to account for those potential side effects.

Is Windows 10 also impacted?

Windows 10 does not appear to be affected by this specific problem in a comparable way. One reason Microsoft implies is that Windows 10 has shifted toward a more limited set of security and servicing changes, while Windows 11 continues to receive ongoing updates to system components and security features.

That difference can make it more likely for older third-party drivers to run into conflicts with newer Windows 11 changes. Microsoft is continuing work on a more permanent fix.