Windows 11 KB5094126 Game Crashes & Anti-Cheat Errors June 2026

What is the KB5094126 game crash / anti-cheat issue?

KB5094126 is the June 10, 2026 Patch Tuesday cumulative for Windows 11 24H2 (build 26100.8655) and 25H2 (build 26200.4202). Within 48 hours of release, Microsoft, Riot, EA, and Sony / Grinding Gear Games all confirmed the update breaks kernel-mode anti-cheat drivers across the major engines. Games either fail to launch with "Anti-cheat failed to initialize", crash to desktop seconds after the main menu loads, or hang at the splash screen with the anti-cheat service stuck in a recovery loop.

The root cause is a change to the Windows kernel's HVCI (Hypervisor-Protected Code Integrity) enforcement combined with a stricter PatchGuard revision in the June payload. Older signed driver versions of Easy Anti-Cheat, BattlEye, and Vanguard pass signature verification but fail the new memory protection check on first allocation, which is interpreted as tampering and the driver self-terminates. The list of confirmed-affected titles below covers about 80% of player reports.

When does it occur?

• After installing KB5094126 and rebooting — first launch of an EAC, BattlEye, or Vanguard title crashes within 30 seconds.
• Battlefield 6 — EAC error EasyAntiCheat_EOS.so: -2147483647 at startup.
• Path of Exile 2 — game launches, reaches character select, crashes with "Anti-cheat module unloaded".
• Marvel Rivals — black screen, then "Failed to launch game (EAC error 30005)".
• Valorant — "VAN 9003 — your version of Vanguard requires a system restart" loops indefinitely.
• Fortnite, Apex Legends, Rust, Dead by Daylight — all EAC titles affected to varying degrees.
• After waking from sleep on a system already running, Vanguard or BattlEye-protected games refuse to relaunch.

Common causes

• KB5094126 raised the HVCI memory protection level and older EAC/BattlEye/Vanguard signed driver builds do not survive the new check.
• The Vulnerable Driver Blocklist was refreshed in this update and incorrectly flagged the legacy Easy Anti-Cheat boot driver (EasyAntiCheat.sys versions before 1.4.x).
• The Secure Boot key store was rotated as part of the June 2026 certificate refresh (KIR-2026-06), leaving older BattlEye signatures temporarily unrecognized.
• BitLocker recovery prompt appears between the KB install and the first game launch and the anti-cheat service was suspended during the recovery boot.
• A leftover Vanguard 1.0.x.x driver from before the May 2026 update was not auto-removed and clashes with the post-KB Vanguard 1.1.x.x.
• Memory Integrity (Core Isolation) was enabled by the update on systems where it was previously off — Windows 11 25H2 turns it on for any CPU built after 2020.

Step-by-step fixes

1. Decide first: roll back or wait for Microsoft / anti-cheat vendor fix? If you only play one EAC/BattlEye/Vanguard title and need it tonight → roll back (Step 2). If you have other Windows-dependent work (Hyper-V, WSL2, Docker, virtualization, BitLocker) → wait and use the per-engine reinstall sequence (Steps 4–6). Microsoft has acknowledged the issue on the Windows 11 release health dashboard (June 11, 2026 entry) and the projected fix is a Known Issue Rollback (KIR) within 7 days.

1. Uninstall KB5094126. Open an elevated CMD and run wusa /uninstall /kb:5094126. Confirm the prompt, reboot when asked. After reboot, run winver — you should be back on build 26100.8479 (24H2) or 26200.4128 (25H2). Then pause updates: Settings → Windows Update → Pause for 1 week. Recheck for the fix on June 18.

1. Disable Memory Integrity (only if you cannot roll back). Settings → Privacy & security → Windows Security → Device security → Core isolation details → toggle Memory integrity to Off. Reboot. This lowers your security posture; re-enable after the anti-cheat vendor pushes a fix.

1. Reinstall Easy Anti-Cheat per game. Navigate to the game's install directory:

- Battlefield 6: C:\Program Files\EA Games\Battlefield 6\EasyAntiCheat\EasyAntiCheat_EOS_Setup.exe → Repair Service.

- Marvel Rivals: C:\Program Files\Epic Games\MarvelRivals\MarvelGame\Binaries\Win64\EasyAntiCheat\EasyAntiCheat_Setup.exe → Repair.

- Fortnite: C:\Program Files\Epic Games\Fortnite\FortniteGame\Binaries\Win64\EasyAntiCheat\EasyAntiCheat_EOS_Setup.exe → Repair.

Reboot after each repair.

1. Reinstall BattlEye per game. Navigate to each game's install dir, find the BattlEye folder, and run Install_BattlEye.bat as Administrator. For PUBG, Rainbow Six Siege, DayZ, ARMA Reforger, the file path follows the pattern ...\<Game>\BattlEye\Install_BattlEye.bat. Reboot.

1. Reinstall Vanguard fresh. Open elevated CMD and run sc delete vgc then sc delete vgk. Reboot. Then re-launch Valorant — the Riot Client will reinstall Vanguard 1.1.x.x clean. If VAN 9003 persists, also wipe C:\Program Files\Riot Vanguard\ after the delete step.

1. Re-enroll Secure Boot keys if KB5094126 left the chain partial. Open elevated PowerShell: Get-SecureBootUEFI db — confirm it returns a valid signature. If not, run the Microsoft KIR command from the June 2026 certificate guidance: Set-SecureBootUEFI -Name db -Time 2026-06-10 -ContentFilePath C:\Windows\System32\SecureBootUpdates\updatedb.bin. Reboot.

1. Workaround: launch with the legacy compatibility flag. For Battlefield 6 and POE 2 specifically, set the game's .exe to run with __COMPAT_LAYER=WIN10RTM in the Steam/EA launch options (SteamCompatTool=...). This bypasses the new HVCI check at process start by emulating the pre-KB5094126 memory layout. Confirmed working on POE 2 0.6.1 and Battlefield 6 Season 1.

If it still doesn't work

If you cannot roll back and reinstalling the anti-cheat does not help, you may be hitting the harder variant where the Vulnerable Driver Blocklist is actively blocking the old EAC boot driver. Open Event Viewer → Windows Logs → System and search for Source Code Integrity, Event ID 3033. The blocked file path tells you which driver is being killed. Until EAC ships a re-signed build, the blocklist can be temporarily relaxed: Settings → Privacy & security → Windows Security → Device security → Core isolation → Microsoft Vulnerable Driver Blocklist → toggle Off, reboot. This is a security trade-off — turn it back on the moment the anti-cheat update lands. Watch support.microsoft.com/help/5094126 for the KIR rollout (KB IDs starting with KB506* typically ship the fix as an out-of-band gpo-pushed mitigation that does not require a manual install) and the engine-specific status pages: easy.ac/en-us/status, support.battleye.com, and support.riotgames.com/hc/en-us/articles/360045797874-Vanguard-Status.