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Games crash with EXCEPTION_ACCESS_VIOLATION after Windows 11 KB5121003

Last verified August 2026Tested against Windows 11 25H2 (OS Build 26200.9168), Windows 11 24H2 (OS Build 26100.9168), KB5121003Well documented

A third-party driver called inpoutx64, installed by RGB lighting, fan-control and hardware-monitoring utilities, stopped getting along with Windows after the 11 August 2026 update KB5121003. Games that load an anti-cheat driver hit it and die, usually with EXCEPTION_ACCESS_VIOLATION. Disabling or removing that driver fixes it; you lose the RGB software's features until its vendor ships an update.

Start here

  1. Check whether inpoutx64 is actually on your PC
  2. Update or uninstall the utility that installed the driver

Microsoft opened this as a known issue on 19 August 2026 and is still investigating whether its own update caused it. It affects Windows 11 24H2 and 25H2. The important thing to establish first is whether inpoutx64 is even on your machine — if it is not, this article is not your problem and none of the steps below will help you.

Symptoms

  • The game window stops responding a few seconds after launch
  • The game closes with no error message at all
  • An EXCEPTION_ACCESS_VIOLATION error appears
  • The whole PC restarts without warning when you start a game
  • It started after 11 August 2026, when KB5121003 installed
  • Other games launch normally; only some titles are affected

Why this happens

inpoutx64 is a kernel driver that no longer behaves after KB5121003

inpoutx64.sys is not part of Windows. It is an old third-party kernel-mode driver that gives a user-space program direct hardware port access, and it is bundled with a range of RGB lighting, fan-control, overclocking and sensor-monitoring utilities. Microsoft says the crashes happen on systems where drivers with names like inpoutx64 are present, and that launching certain games is what triggers it. Because the driver sits in kernel space alongside a game's anti-cheat driver, the fault takes the game — or the whole machine — down with it.

Check whether inpoutx64 is actually on your PC · Update or uninstall the utility that installed the driver · Disable the driver in the registry (Microsoft's workaround) · Delete the driver service and file (Embark Studios' workaround)

Only some games trip it

The titles named in reports so far are ARC Raiders, MARVEL Tokon: Fighting Souls and THE FINALS. Microsoft has not published the mechanism, so the list is what has been reported rather than a complete set. Games that never load a kernel-level anti-cheat driver are unlikely to be affected, which is why most of your library keeps working.

Check whether inpoutx64 is actually on your PC

Fixes

Check whether inpoutx64 is actually on your PC

about 2 min

This decides whether the rest of the article applies to you. Nothing here is worth doing if the driver is not installed.

Applies to: Windows 11 24H2, Windows 11 25H2

  1. Press the Windows key, type cmd, and open Command Prompt. You do not need administrator rights for this check.
    sc query inpoutx64
  2. If the reply is "The specified service does not exist as an installed service", the driver is not there and this is a different problem. Read "When something else is wrong" below.
  3. If it returns a service with a STATE of RUNNING, this article applies. Confirm KB5121003 is installed too.
    wmic qfe get HotFixID | findstr KB5121003

Confirmed by the vendor.

Source: Microsoft, Microsoft

Update or uninstall the utility that installed the driver

about 10 min

The cleanest outcome is the vendor shipping a build that no longer needs this driver. Failing that, removing the app is fully reversible — you can reinstall it later.

Applies to: Windows 11 24H2, Windows 11 25H2

  1. Work out which app owns it. Candidates are your RGB lighting software, motherboard tuning and fan-control suites, and hardware sensor monitors. If several are installed, start with the one you installed most recently.
  2. Check that app for an update first. A vendor patch that drops inpoutx64 solves this without you losing anything.
  3. If there is no update, uninstall the app from Settings > Apps > Installed apps, then restart.
  4. Re-run the check from the previous fix. Some uninstallers leave the driver service behind, in which case you still need one of the steps below.
    sc query inpoutx64

Source: Microsoft, Windows Latest

Disable the driver in the registry (Microsoft's workaround)

Advancedabout 5 min

This is the workaround Microsoft published. It stops the driver loading at boot without deleting anything, so it is straightforward to undo.

Applies to: Windows 11 24H2, Windows 11 25H2

Before you do this

This edits the registry. Back the registry up before you change anything — Microsoft's own guidance on this issue says the same. Disabling the driver can stop RGB lighting, fan curves, macros or sensor readouts working, and can make the software that installed it misbehave.

First:

  • Export a registry backup first: in Registry Editor, File > Export, All, and save the .reg file somewhere you can find it
  1. Press the Windows key, type regedit, and open Registry Editor.
  2. Paste this path into the address bar at the top and press Enter.
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\inpoutx64
  3. On the right, double-click the value named Start and set Value data to 4. That is the code for "disabled".
  4. Close Registry Editor and restart the PC, then launch the game.
  5. To undo it later, set Start back to the number it was before — 1 or 3 in most cases — or import the .reg backup you exported.

Confirmed by the vendor.

Source: Microsoft

Uninstall KB5121003

Advancedabout 15 min

It removes the trigger, but it also removes that month's security fixes. Treat it as a last resort rather than a first move.

Applies to: Windows 11 24H2, Windows 11 25H2

Before you do this

KB5121003 is a security update. Removing it leaves your PC without the August 2026 security fixes until you reinstall it, and Windows Update will try to reinstall it on its own. Prefer disabling the driver over rolling back the update.

  1. Open Settings > Windows Update > Update history.
  2. Scroll to the bottom and select Uninstall updates.
  3. Find KB5121003 in the list and select Uninstall, then restart.
  4. Pause updates for a week or two so it does not reinstall immediately: Settings > Windows Update > Pause updates. Unpause once a fixed driver or a Microsoft fix is available.

Source: Microsoft, Windows Latest

Delete the driver service and file (Embark Studios' workaround)

Can cause data lossabout 10 min

This is what ARC Raiders' developer told players to do. It removes the driver outright rather than disabling it, so use it only if the registry route did not stick.

Applies to: Windows 11 24H2, Windows 11 25H2

Before you do this

This deletes a driver file. If the utility that installed it does not put it back, you will lose whatever that utility used it for — RGB control, fan curves, macros, sensor monitoring — until you reinstall the application. Do not delete any file other than the one named here.

First:

  • Create a System Restore point: press the Windows key, type "Create a restore point", open it, select your system drive and choose Create
  • Know which application installed the driver, so you can reinstall it if you need those features back
  1. Press the Windows key, type cmd, right-click Command Prompt and choose Run as administrator.
  2. Stop the driver service.
    sc stop inpoutx64
  3. Delete the service registration.
    sc delete inpoutx64
  4. Open C:\Windows\System32\drivers, find inpoutx64.sys, and delete it. Delete nothing else in that folder.
  5. Restart the PC and launch the game.

Confirmed by the vendor.

Source: Windows Latest

Known issues

  • Microsoft has an open known issue for games becoming unresponsive after KB5121003 on Windows 11 24H2 and 25H2, opened 19 August 2026 and still marked Investigating. Microsoft has not said whether its own update caused it.

    Affects Windows 11 25H2 (OS Build 26200.9168), Windows 11 24H2 (OS Build 26100.9168) · Status: workaround only

If none of this worked

If `sc query inpoutx64` says the service does not exist, stop here — this is not your crash. The same symptoms have plenty of other causes: an unstable memory overclock or XMP/EXPO profile, an overheating or power-starved GPU, a corrupted shader cache, or a game update that shipped its own bug. Check whether the crash predates 11 August 2026, and whether other players of the same game are reporting it this week. If it only happens in one game and started with a game patch rather than a Windows one, the developer's own support channel is the faster route.

Common questions

Is inpoutx64.sys malware?
No. It is a legitimate, very old third-party driver that gives software direct access to hardware I/O ports. Plenty of RGB lighting, fan-control, overclocking and sensor-monitoring tools bundle it. It is not a Windows component, which is why removing it does not damage the operating system — it only affects whichever application relies on it.
Which app installed it on my PC?
Windows does not record that, and the driver ships inside so many utilities that there is no reliable lookup. Work backwards from what you have installed: motherboard tuning suites, RGB lighting controllers, fan-curve tools and hardware monitors are the usual candidates. If uninstalling one does not remove the driver service, uninstall it and then use the registry or deletion step.
Should I just uninstall the Windows update?
Prefer not to. KB5121003 is a security update, and removing it leaves the PC exposed until you reinstall it — while Windows Update keeps trying to put it back. Disabling the inpoutx64 driver targets the actual trigger and leaves your security patches in place.
My game is not on Microsoft's list. Could this still be it?
Possibly. Microsoft names ARC Raiders, MARVEL Tokon: Fighting Souls and THE FINALS because those are the titles in the reports it received, not because it has established the full set. If your crashes started on 11 August 2026, the driver is present, and disabling it stops the crashes, the cause is the same regardless of the title.
Will Microsoft fix this?
The issue is open and marked Investigating as of 21 August 2026, with Microsoft saying it is still working out the relationship between the RGB components and the games that trigger the fault. There is no fix date. Watch the Windows release health page for version 25H2, and check your RGB utility for updates — a vendor build that drops the driver would resolve it just as well.

Did this fix work?

If a step is wrong, outdated, or did not help, telling us is the fastest way to get it corrected. Reports are reviewed before new articles.

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Related problems

Sources

  • Windows 11, version 25H2 known issues and notificationsOfficial

    Microsoft · Release notes · checked Aug 22, 2026

    • Microsoft opened a known issue on 2026-08-19 for games becoming unresponsive after KB5121003, status Investigating
    • Microsoft links the crashes to peripherals or internal components with RGB lighting that install drivers named similarly to inpoutx64
    • Symptoms Microsoft lists are the game hanging, closing without notice, EXCEPTION_ACCESS_VIOLATION, and unexpected device restarts
    • ARC Raiders, MARVEL Tokon: Fighting Souls and THE FINALS are the titles named in reports
    • Microsoft's workaround is setting HKLM\SYSTEM\CurrentControlSet\Services\inpoutx64\Start to 4 and rebooting
    • Microsoft warns that disabling the driver can break RGB features and the software that controls them
    • Affected platforms are Windows 11 version 25H2 and version 24H2
  • KB5121003: Windows 11 update, August 11, 2026 (OS Builds 26100.9168 and 26200.9168)Official

    Microsoft · Support page · checked Aug 22, 2026

    • KB5121003 was released on 11 August 2026 as OS Builds 26100.9168 and 26200.9168
    • KB5121003 is a security update and ships with servicing stack update KB5123304
    • The KB page repeats the games-becoming-unresponsive known issue and names inpoutx64
  • Windows 11's August update is breaking games, and Microsoft is investigating after a studio blamed the updateReputable

    Windows Latest · News · checked Aug 22, 2026

    • An Embark Studios developer posted on Discord that the studio is aware of a new crash introduced by KB5121003
    • Embark's workaround is sc stop inpoutx64, sc delete inpoutx64, then deleting inpoutx64.sys from C:\Windows\System32\drivers
    • inpoutx64.sys is a third-party kernel-mode port I/O driver that ships with hardware and lighting utilities, not a Windows component
    • Removing the driver can disable RGB, fan control, macro and sensor features in the utility that installed it