KB5121003 problems can affect Windows 11 after the August 11, 2026 security update. It moves 24H2 to build 26100.9168 and 25H2 to build 26200.9168.
The important change since this guide was first published is Microsoft’s investigation of game crashes reported after the update. Microsoft now says the confirmed problem is linked to RGB-lighting components that install a driver with a name similar to inpoutx64—not to the Windows update itself. Microsoft marked the issue resolved on August 26, 2026.
If a game freezes, closes, shows EXCEPTION_ACCESS_VIOLATION, or restarts the PC after KB5121003, restart Windows and check for updates. Microsoft is automatically applying a block that prevents the affected inpoutx64 driver from loading on unmanaged consumer and business PCs. If the crash continues, update or remove the RGB-control software supplied with the affected peripheral, then report the case through Feedback Hub. Do not uninstall the security update as your first step.
Microsoft received reports involving ARC Raiders, MARVEL Tōkon: Fighting Souls, and THE FINALS. Reported symptoms included a frozen or abruptly closed game, an EXCEPTION_ACCESS_VIOLATION error, and an unexpected restart.
Microsoft’s Windows release-health record says its investigation confirmed that the issue is related to peripherals or internal components with RGB-lighting features. Those components can install drivers or code with names similar to inpoutx64. Launching an affected game then triggers the failure.
This distinction matters: the problem appeared after KB5121003 and later updates, but Microsoft says Windows Update is not the underlying cause.
How Microsoft Resolved the KB5121003 Game Crash
Microsoft released a targeted compatibility block that prevents the affected inpoutx64 driver from loading. On an affected PC, Windows may display a message explaining that the driver was disabled; the game should then launch normally.
The block began propagating automatically to consumer and business devices not managed by an IT department. Microsoft says a restart is required. The initial rollout targeted devices with ARC Raiders installed, with coverage being expanded for MARVEL Tōkon: Fighting Souls. Embark Studios resolved the reported problem for THE FINALS.
The block is also scheduled to be included in the September 2026 Windows security updates and later releases. Enterprise-managed devices do not receive this mitigation automatically, so their administrators should use Microsoft’s documented workaround.
The disabled driver may belong to RGB-control or hardware-monitoring software. If Windows blocks it, do not download a replacement DLL or driver from an unofficial website. Check the peripheral or motherboard maker’s support page for a newer compatible version.
What to Do If a Game Still Crashes
- Restart Windows. Microsoft requires a restart for the automatic driver block to take effect.
- Check Windows Update. Open Settings > Windows Update, select Check for updates, install available security and driver updates, and restart again.
- Update the game and launcher. Install current patches from the game’s normal launcher.
- Update RGB software from its maker. Check the official support page for your keyboard, mouse, motherboard, lighting controller, or other RGB component.
- Temporarily remove the RGB utility. If the crash began while that utility or driver was installed, uninstall the utility through Settings > Apps > Installed apps, restart, and retest. Lighting effects may stop working until compatible software is installed.
- Send a report. Press Windows key + F to open Feedback Hub. Include the game name, crash symptom, Windows build, and the RGB hardware or software installed.
If Windows restarts unexpectedly or shows a blue screen outside these games, use our Windows BSOD troubleshooting guide to record the stop code and check drivers and hardware.
Enterprise Workaround for the inpoutx64 Driver
This registry workaround is intended for enterprise-managed devices that do not receive Microsoft’s automatic mitigation. Home users should wait for the automatic block, update the RGB utility, or remove that utility first.
- Back up the registry and note the current value before changing it.
- Open Registry Editor as an administrator.
- Go to
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\inpoutx64. - Open the Start value and change its value data to 4.
- Close Registry Editor and restart the PC.
This disables the driver and can affect the software or lighting feature that depends on it. Microsoft documents the same steps and reversal warning on its release-health page. Restore the original value only when a compatible driver is available or your IT administrator directs you to do so.
Editing the wrong registry value can prevent software or Windows components from working. Make a registry backup first. If this is a managed work or school PC, let your IT administrator apply the workaround.
If KB5121003 Will Not Install
A failed installation is separate from the confirmed RGB-driver issue. Start with ordinary Windows Update repair steps:
- Restart the PC and disconnect nonessential USB devices.
- Open Settings > System > Storage and make sure the system drive has free space.
- Run the Windows Update troubleshooter from Settings > System > Troubleshoot > Other troubleshooters.
- Return to Windows Update and retry once.
- If an error code appears, record it before trying a repair.
For error 0x80073712, follow our dedicated Windows Update error 0x80073712 guide. It covers DISM, System File Checker, the update cache, and Windows repair options in the safest order.
How to Install KB5121003 Manually
Use manual installation only when Windows Update repeatedly fails and Windows servicing is otherwise healthy.
- Open Settings > System > About and confirm whether the PC runs Windows 11 24H2 or 25H2 and whether it uses x64 or Arm64 architecture.
- Open the official Microsoft Update Catalog results for KB5121003.
- Choose the package matching the Windows version and architecture. Do not guess between 24H2, 25H2, x64, and Arm64.
- Download the package, run it, and restart when prompted.
- Open Settings > Windows Update > Update history and confirm the result.
The Catalog packages are several gigabytes, so a manual download is not the best first fix for a slow or unstable connection.
What KB5121003 Changes
KB5121003 is a cumulative security update for Windows 11 24H2 and 25H2. Microsoft’s official KB5121003 release notes list these notable changes:
- Security improvements and fixes included in earlier July 2026 updates.
- Additional targeting data for PCs eligible to receive newer Secure Boot certificates.
- Removal of the experimental Drop Tray, previously called Drag Tray, and its Multitasking setting on devices where it appeared.
- Updates to several Windows AI components on supported systems.
- A servicing-stack update, KB5123304, intended to improve update-installation reliability.
Windows 11 24H2 Home and Pro reach end of updates on October 13, 2026. That support deadline is separate from the KB5121003 game issue.
Should You Uninstall KB5121003?
Usually, no. KB5121003 is a security update, and Microsoft’s confirmed game issue is being handled by blocking the incompatible RGB-related driver. Restart, install current updates, and update or temporarily remove the RGB utility before considering removal of the Windows update.
If Windows itself cannot start or the PC develops a serious repeatable problem immediately after installation, use Settings > Windows Update > Update history > Uninstall updates or Windows Recovery Environment as a temporary recovery step. Back up important files when possible and reinstall the latest security update after the underlying driver or software conflict is resolved.
Frequently Asked Questions
Does KB5121003 cause game crashes?
Microsoft says the confirmed crashes reported after KB5121003 are not caused by Windows Update itself. They are linked to certain RGB-lighting peripherals or components that install a driver with a name similar to inpoutx64.
Is the KB5121003 game problem fixed?
Microsoft marked the issue resolved on August 26, 2026. An automatic compatibility block disables the affected driver on eligible unmanaged PCs, and a restart is required.
Which games were named by Microsoft?
Microsoft named ARC Raiders, MARVEL Tōkon: Fighting Souls, and THE FINALS in reports. Similar symptoms in another game should still be reported through Feedback Hub so Microsoft and the hardware or game vendor can investigate.
What is inpoutx64?
In this case, inpoutx64 refers to a low-level driver or code component installed by some RGB-lighting peripherals or internal hardware utilities. Microsoft blocks the affected driver because launching certain games while it is present can trigger a crash.
Should I delete inpoutx64 manually?
No. Do not delete driver files manually or download replacements from unofficial sites. Let Windows apply the block, or update or uninstall the related RGB utility through normal Windows and vendor-supported methods.
Keep KB5121003 Installed and Fix the Driver Conflict
The current evidence does not support removing KB5121003 from every gaming PC. Microsoft traced the confirmed crashes to an RGB-related driver and released a targeted block, so the best path is to restart, keep Windows updated, and update or remove the affected hardware utility if the problem remains.
For an installation failure, treat the error code as a separate Windows Update problem. Use the built-in troubleshooter first, then move to component repair or a correctly matched Catalog package only when needed.
