Windows 11 KB5121003 now crashing games and causing Windows Hello issues

Windows 11's KB5121003 security update is triggering game crashes and other problems for some users. The mandatory patch, released on August 11, moves 25H2 devices to build 26200.9168 and 24H2 devices to build 26100.9168, and it fixes more than 420 security issues in total. Microsoft's official release notes for the update currently list no known issues.

Arc Raiders and The Finals are crashing after the update

Players of Embark Studios' Arc Raiders and The Finals reported crashes shortly after installing the update, along with unexpected reboots. Embark confirmed the problem in a Discord post, saying it is aware of a new crash tied to KB5121003 and that its team is working on a fix. Affected users have seen errors including a hang detected on GameThread and EXCEPTION_ACCESS_VIOLATION messages.

The cause is a broken third-party driver, not the update itself

Embark traced the crashes to inpoutx64.sys, a third-party kernel-level port access driver used by some hardware utilities, saying the update changed something that broke compatibility with that file. The studio has published a workaround that stops and deletes the inpoutx64 service through Command Prompt, then removes the driver file from the Windows system32 drivers folder. Some affected players found the driver had been installed by tools such as Razer's update utility. Similar crash reports have surfaced for Marvel Tōkon: Fighting Souls and for some anti-cheat software, and removing KB5121003 entirely has also resolved the issue for affected users.

Windows Hello and display issues are also being reported

Windows Latest had also mentioned that they had seen isolated reports of Windows Hello failing after the update, including one case where the PIN must be re-enrolled after every reboot because the credential key becomes corrupted each time it regenerates and another where the existing Hello container fails to load. There are also scattered reports of display refresh rates dropping unexpectedly, black screens, and broken HDR behavior, which the outlet links to display-related changes bundled into the update.

What affected users should do

Users hitting game crashes can remove the inpoutx64 driver or the software that installed it. For other problems, the update can be removed through Settings, Windows Update, Update History, and Uninstall Updates. However, this should be a last resort given the patch also closes an actively exploited zero-day tracked as LegacyHive. Waiting for an official fix or the September 2026 update is the safer option unless a PC is unusable.