inpoutx64.sys, is present. The immediate practical fix is to address that driver rather than reflexively remove the security update: KB5121003 is the mandatory August patch for Windows 11 24H2 and 25H2, moving systems to builds 26100.9168 and 26200.9168 respectively.
Windows Latest first reported the failures after players began tying new crashes and occasional reboots to the update. Embark Studios, which develops both games, has since acknowledged the problem in its Discord channels and identified inpoutx64.sys as the common file in its workaround. That is meaningful corroboration: this is no longer only a collection of post-update anecdotes, though it remains a compatibility failure affecting a subset of PCs rather than evidence that KB5121003 broadly breaks games.
Microsoft’s release information does not yet list the game crashes as a known issue. That leaves affected users in an uncomfortable position: a monthly security update remains installed on machines where a legacy, kernel-level utility driver can now destabilize modern anti-cheat-protected games.
The collision is with a legacy hardware-access driver
inpoutx64.sys is not part of Windows 11 or either game. It is an old kernel-mode port-access driver associated with Highresolution Enterprises’ InpOut32/InpOutx64 components. Its purpose is to let software access low-level hardware resources, which made it useful to older peripheral-control, system-tuning, sensor-reading, and RGB tools.
The driver’s age is the issue worth focusing on. File records identify the commonly encountered inpoutx64.sys driver as version 1.2, with origins dating to 2008. It has continued to surface because applications can quietly bundle and install it rather than because users intentionally install a product named InpOutx64.
Microsoft community support threads and hardware-software discussions have previously linked the driver to utilities such as X-Mouse Button Control, ZenTimings, OpenRGB-related tools, OEM control software, and other programs that need direct hardware access. That does not mean every installation comes from the same application. A Razer updater was one suspected source in reporting collected by Windows Latest, while users have also traced the driver to laptop-management and tuning utilities.
Embark’s diagnosis is narrower than some early social-media claims. The studio says the crash concerns how inpoutx64.sys behaves after KB5121003, not that every Windows 11 PC with the August patch is affected. Players reporting success after uninstalling the update have established a useful correlation, but that rollback does not prove the cumulative update alone is defective in isolation. The driver-and-game combination is the actionable fault line.
Embark’s workaround removes a dependency, not a Windows component
Embark advises affected players to stop and delete the inpoutx64 service, remove C:\Windows\System32\drivers\inpoutx64.sys, optionally clear its service registry entry, and restart Windows. Community reposts of the studio’s Discord notice show the same instructions for both ARC Raiders and THE FINALS.
That procedure may restore the games, but it has a consequence that the short workaround can obscure: deleting the driver can disable features in the software that installed it. RGB controls, fan settings, peripheral macros, sensor monitoring, or motherboard-tuning functions may stop working until the originating application is updated, reconfigured, or removed. On laptops, that risk deserves particular caution because vendor utilities can be tied to performance profiles and thermal controls.
For that reason, the best first step is not to delete a file from System32 blindly. Identify what installed it. In an elevated Command Prompt, administrators can inspect the service with:
sc qc inpoutx64
The command will not always reveal the parent application, but it confirms whether the service exists and where Windows expects the driver to load from. Check installed applications and any recently updated peripheral, RGB, overclocking, or system-monitoring utilities before removing the driver. If a specific application is identified, uninstalling or updating that application is cleaner than leaving an orphaned kernel-driver service behind.
A restore point or a full backup is sensible before making service and registry changes. The driver is not malware merely because it is old or because anti-cheat software objects to it; it is legitimate third-party code with a very broad hardware-access role. But its kernel-level privileges and long-lived distribution through unrelated utilities make it exactly the kind of component that can become incompatible when Windows or anti-cheat software tightens enforcement.
Uninstalling KB5121003 should be the last temporary measure
The August update contains security fixes, and the patch should not be treated as optional just because a game crashes on a particular configuration. Windows Latest characterized the release as fixing more than 400 security issues, while Microsoft’s Security Update Guide remains the authoritative record for the individual vulnerabilities covered by August’s Patch Tuesday releases.
Removing KB5121003 can be a reasonable short-term containment step for a home machine where the owner cannot safely remove or update the software that installed inpoutx64.sys. It is a weaker choice for work systems, shared PCs, or devices subject to patch-management requirements. In those cases, an IT administrator should document the exception, identify the driver’s owner, and plan to reapply KB5121003 as soon as the incompatible dependency is eliminated.
The distinction matters operationally. A user who uninstalls the cumulative update but keeps the legacy driver has only deferred the conflict, because a future cumulative update or game anti-cheat revision may confront the same component again. A user who removes inpoutx64.sys without identifying its parent software may find that a later utility update simply reinstalls it.
For managed fleets, the sensible approach is to query for the service and driver path before making a broad rollback decision. Endpoint-management tools can inventory C:\Windows\System32\drivers\inpoutx64.sys and the HKLM\SYSTEM\CurrentControlSet\Services\inpoutx64 service key, then correlate affected machines with installed OEM and peripheral-management software. That creates a targeted remediation list instead of turning a gaming issue into an organization-wide security-patch exception.
Other reported graphics problems remain unproven
Windows Latest also collected reports of black screens, refresh-rate drops, HDR failures, anti-cheat crashes, and problems in Marvel Tōkon: Fighting Souls after KB5121003. Those claims should be treated separately from the Embark-confirmed inpoutx64.sys crash pattern.
There is no public evidence yet that all of those symptoms share one root cause. Display behavior is especially vulnerable to coincidental graphics-driver updates, monitor firmware, HDR configuration changes, overlays, and game-specific patches. Users seeing those issues should record the Windows build, GPU driver version, display model, game, and crash or Event Viewer details before concluding KB5121003 is responsible.
PC Gamer’s coverage of KB5121003 has focused on performance-related changes in the update rather than the Embark crash reports. That split reinforces the current evidence: the update is installing and operating normally on many systems, while a specific legacy driver is causing a serious failure in an identifiable subset of gaming PCs.
What affected players should do now
Players who began crashing only after installing KB5121003 should first confirm they are running Windows 11 build 26100.9168 or 26200.9168 and check whether the inpoutx64 service or driver file exists. If it does, identify and update or remove the utility that installed it before resorting to removal of the Windows security patch.
Embark is working on a longer-term game-side fix, but it has not published a delivery date or explained precisely which post-update behavior changed. Microsoft has also not yet added the issue to KB5121003’s known-problems list. Until one of those vendors provides a durable remedy, the practical resolution is to remove the obsolete dependency where possible, verify that the hardware utility it belonged to still works as intended, and keep the August security update installed.