If your games started crashing to desktop or rebooting your PC in the last few days, the Windows 11 August update is the most likely culprit. Since KB5121003 began rolling out on 11 August 2026, players of ARC Raiders, THE FINALS and a handful of other titles have been reporting sudden crashes, hangs and in some cases full system restarts mid-match — and the developer of the two Embark titles has publicly pinned the blame on a single old kernel driver that the update appears to have upset.

Windows 11 logo, illustrating the Windows 11 August update game crashes traced to KB5121003
Image: Microsoft, via Wikimedia Commons

The good news is that there is a fix, it takes about a minute, and you do not have to remove a security update that patches more than 400 vulnerabilities to get it.

What is causing the Windows 11 August update game crashes

KB5121003 is the August 2026 cumulative update for Windows 11, taking version 24H2 to build 26100.9168 and version 25H2 to build 26200.9168. We covered what the August Patch Tuesday update changes when it shipped.

According to Windows Latest, which spoke to affected players and read Embark Studios’ message to its community on Discord, the studio has identified the crash as a conflict involving a file called inpoutx64.sys, which it says changed with the Windows update. Embark said it is working towards a long-term fix and, in the meantime, published a workaround that removes the file so the game runs normally again.

Crucially, inpoutx64.sys is not a game file and not a Microsoft file. It is the 64-bit driver from InpOut32/InpOutx64, an open-source library that gives ordinary applications direct access to hardware ports. It gets dropped into C:\Windows\System32\drivers\ by hardware utilities you may have installed and forgotten about — RGB lighting control tools, fan and memory-timing utilities, and vendor updater apps are all known to bundle it. One player traced their copy to a Razer update tool.

It is also abandonware. The developer’s own download page for the project is blunt about it:

NOTE: This project is legacy and no longer actively supported by me. I am unable to build and sign the driver in any case.

That is the real story here: a signed kernel-mode driver that nobody maintains any more, quietly shipped inside consumer utilities, sitting one Windows servicing change away from crashing your machine.

Symptoms to check before you change anything

Only apply the fix below if the pattern matches. Reported symptoms include the game closing to desktop mid-session, errors reading Hang detected on GameThread or EXCEPTION_ACCESS_VIOLATION, and — on some machines — the PC rebooting outright when the crash hits. The common thread is that it started after 11 August.

To confirm which build you are on, open Settings > System > About and look at the OS build under Windows specifications. If it reads 26100.9168 or 26200.9168, you have KB5121003 installed.

One thing that is not this bug: Windows restarting two or three times during the update installation itself. That is the Secure Boot certificate rollout doing its work, and it is expected.

Fix 1: disable the driver (reversible, try this first)

This stops the driver loading without deleting anything, so you can undo it in seconds if it does not help.

  1. Press Start, type cmd, right-click Command Prompt and choose Run as administrator.
  2. Stop the service: type sc stop inpoutx64 and press Enter.
  3. Prevent it loading at boot: type sc config inpoutx64 start= disabled and press Enter. The space after start= is required — that is the syntax Microsoft documents for sc config, and the command fails without it.
  4. Restart your PC and launch the game.

To reverse this later, run sc config inpoutx64 start= demand from the same elevated prompt, which sets the driver to load on demand.

Fix 2: remove the driver (Embark’s own workaround)

If disabling it is not enough, the studio’s published workaround goes further and deletes the file.

  1. Open Command Prompt as administrator, as above.
  2. Run sc stop inpoutx64.
  3. Run sc delete inpoutx64.
  4. Close the window, open File Explorer and go to C:\Windows\System32\drivers\.
  5. Find inpoutx64.sys and delete it.

Be aware of the trade-off before you do this. Whatever utility installed the driver may lose the low-level hardware access it wanted — your RGB software may stop detecting lighting, or a fan or timing tool may stop reading sensors. Many of those apps will simply reinstall the driver the next time you launch them, at which point the crashes can return. If that happens, work out which app is putting it back and decide whether you need that app more than you need the game.

Fix 3: uninstalling the update (last resort)

Removing KB5121003 does stop the crashes — several players have confirmed it — but we would not recommend it. This update fixes more than 400 security issues. Rolling it back to keep playing a game trades a real security exposure for a convenience. If you must, the path is Settings > Windows Update > Update history > Uninstall updates, and you should reinstall it as soon as a proper fix lands.

Where Microsoft stands

Update, 26 August 2026: Microsoft has now acknowledged the problem. It opened a known issue on the Windows release health dashboard on 19 August, last updated 21 August, under the heading that it has received reports of certain games becoming unresponsive. The status is still Investigating. Microsoft’s write-up ties the issue to peripherals or internal device components with RGB lighting features, says such devices may install drivers or code components with file names similar to inpoutx64, and identifies the trigger as launching certain games. It names ARC Raiders, MARVEL Tōkon: Fighting Souls and THE FINALS, and lists the symptoms as the game becoming unresponsive, the game closing without notice, an EXCEPTION_ACCESS_VIOLATION error, or the device restarting without warning. Both Windows 11 25H2 and 24H2 are listed as affected; no Windows Server versions are.

Microsoft’s own workaround is the same idea as Fix 1 above, done through the registry rather than sc. It says to open Registry Editor, go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\inpoutx64, double-click the Start value, set the Value data to 4, and restart. Back up the registry first — Microsoft says so explicitly, and it is the right advice. Microsoft gives the same warning we did about the trade-off: disabling the key can break RGB features on peripherals or components, or the software that controls them, and you can undo it by restoring the previous value.

Setting Start to 4 is what sc config inpoutx64 start= disabled does under the hood, so if you already applied Fix 1 you do not need to do this again. Microsoft has not shipped a permanent fix and says it is still working out the relationship between the RGB components and the games involved.

It is worth noting that Microsoft opened this issue eight days after shipping the update, and days after a game studio had already named the cause and given its players a workaround. In the meantime, it is worth taking two minutes to look at what else has quietly installed kernel drivers on your PC in the name of controlling a case fan.

Sources: Windows Latest, Highresolution Enterprises (InpOut32), Microsoft Windows release health