Windows 11 PCs reboot after the KB5121003 game crash, Microsoft confirms (August 21, 2026)

What is new on August 21

The crash pattern itself was established days ago, in the August 16 post, and Microsoft's acknowledgement arrived in the August 20 post. What August 21, 2026 adds is a worse symptom, reported as the confirmation spread.

gHacks reports that the bug produces a game crash with an EXCEPTION_ACCESS_VIOLATION error and that, in some cases, the PC reboots automatically after the crash. Not a hang, not a return to the desktop: a restart, without a prompt. The affected games are the same three, Arc Raiders, Marvel Tokon: Fighting Souls and The Finals, on builds 26200.9168 and 26100.9168 from the August 11 update.

Nothing new was acknowledged by Microsoft on August 21, 2026 itself. The vendor position is the one it took two days earlier, and gHacks is the same-day record of a confirmed problem with the cause still unassigned.

What Microsoft's entry actually says

The summary on Microsoft Learn release health, in the entry opened on August 19, 2026 at 17:50 PT, reads 'Some games become unresponsive when certain drivers are present. This issue is related to peripherals with RGB features'. The drivers it points at have 'file names similar to inpoutx64'.

Two details in that wording are worth reading closely. Microsoft describes the trigger as peripherals with RGB features, which is a hardware category rather than one vendor's software. And the phrase 'file names similar to inpoutx64' is deliberately loose, which suggests more than one file name is in play.

That looseness has a practical consequence. If you go looking for exactly inpoutx64.sys and do not find it, the entry does not promise your PC is unaffected. It points at a family of port-access drivers shipped with lighting and fan-control hardware.

Confirmed is not the same as fixed

gHacks makes the state of play plain: Microsoft confirmed the issue on Windows 11 25H2 and 24H2 and was still investigating whether the update or third-party software was responsible. That is an unusual position for a user to sit in. The defect is official, the blame is not assigned, and no remedy carries Microsoft's name.

It matters because responsibility decides the shape of the fix. If the change in Windows is at fault, the repair arrives in a Windows update. If the driver is at fault, it arrives from the hardware utilities that ship it, on their own schedules. A person with a restarting PC cannot wait on that distinction being settled.

So the honest summary for August 21, 2026 is that the only actions available are the ones users and a game studio worked out, and they carry costs Microsoft has not agreed to.

What an unannounced restart costs

A crash that closes a game costs you a match. A restart without warning costs whatever else was open: documents that were not saved, downloads in flight, a stream or a call that simply ends. It is also the symptom most likely to be misread as failing hardware, which sends people buying power supplies and memory to chase a software defect.

The other cost is diagnostic. Once a PC restarts, the on-screen evidence is gone, and what is left is whatever the event log captured. If you are trying to establish that your restarts match this known issue rather than something else, note the time of each one before you start changing anything.

What you can do today

The steps have not changed since the crashes were identified, and neither have their costs. In order:

1. Check for the driver. Open C:\Windows\System32\drivers and look for inpoutx64.sys or a similarly named port-access driver installed by lighting or fan-control software.

2. If one is there and a named game crashes or restarts the PC, open Command Prompt as administrator and run sc stop inpoutx64, then sc delete inpoutx64. Then delete the file and restart.

3. Accept what that costs. The RGB or hardware utility that installed the driver loses the function that needed it. This is the studio's guidance, not Microsoft's.

4. Until you have done that, save your work and close anything that matters before launching one of the affected games, because the restart arrives without a prompt.

5. Do not uninstall KB5121003 to keep playing. The August update carries the month's security fixes, and a game is not worth that trade.

6. Write down the time of each unexpected restart. If a fix ships and the restarts continue, that record is what separates this known issue from a hardware fault.

7. If you would rather not remove a kernel driver by hand: Get XLAnt.