Rainbow Six Siege Crashing on PC: How to Fix It (2026)

Rainbow Six Siege crashing on PC is usually fixed by verifying the game files, repairing Ubisoft Anti-Cheat from the game’s Sentinel folder, updating Windows and your GPU driver, and running the game as administrator — the order Ubisoft’s own PC troubleshooting guide uses. If Siege crashes at launch or takes Windows down during the “Install Security Update” step, check the Windows updates first: in October 2026 Ubisoft confirmed that the Windows Preview updates KB5124010 and KB5121794 caused exactly that crash.

Quick fix table

What you see	Most likely cause	Fix
Crash during “Install Security Update”, or the whole PC crashes at launch	Windows Preview updates KB5124010 / KB5121794	Fix 1
Game closes at the BattlEye or Ubisoft splash	Corrupted files or anti-cheat install	Fix 2, Fix 3
”Failed to start the driver service” (error 50, 1392, 1450)	Ubisoft Anti-Cheat	Siege anti-cheat error fix
Random crash to desktop mid-match	Driver, overlay or overclock	Fix 4, Fix 6
DirectX 12 / “device removed” crash	GPU driver or unstable GPU overclock	Fix 4, DX12 section
Hitches and FPS drops, but no crash	A performance problem, not a crash	Siege stuttering fix

Fix 1 — Remove the Windows Preview updates Ubisoft flagged

Ubisoft’s bug reporter entry R6S-3173 (“R6 crashes PC after recent update during ‘Install Security Update’ sequence”, last updated 19 October 2026) describes the game stopping at the BattlEye loading window, asking for a restart to apply a security patch, then crashing Windows every time. Ubisoft’s verified workaround says the issue is related to the latest Windows Preview updates and recommends uninstalling:

• KB5124010 (Build 26200.9550)
• KB5121794

To remove them:

1. Open Settings → Windows Update → Update history.
2. Scroll down and choose Uninstall updates.
3. Uninstall KB5124010 and KB5121794 if they are listed, then restart.
4. Launch Siege and let BattlEye finish its update before you join a match.

Both are preview updates, which Windows installs only if you opted into optional or early updates. If neither is in your list, this isn’t your crash; move on to Fix 2. Ubisoft marks the issue as a workaround, not a permanent fix, so check the bug reporter for newer guidance before removing updates from a fully patched PC.

Fix 2 — Verify the game files

Ubisoft says Siege depends on files that must be present and intact for it to run on Windows; corrupted or missing files cause crashes and performance problems. Verify them in whichever launcher you own the game on:

• Ubisoft Connect: Games → Rainbow Six Siege → Properties → Verify files.
• Steam: right-click Rainbow Six Siege → Properties → Installed Files → Verify integrity of game files.
• Epic Games Launcher: Library → … on Siege → Manage → Verify.

Fix 3 — Repair or reinstall Ubisoft Anti-Cheat

Siege uses BattlEye and Ubisoft Anti-Cheat. Ubisoft Anti-Cheat installs automatically with the game, and Ubisoft’s support article gives a repair path when that install gets corrupted:

1. Open the game’s installation folder. The default Ubisoft Connect location is C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\games.
2. Go into the Sentinel folder.
3. Right-click UbisoftAntiCheatInstaller.exe → Run as administrator → choose Repair. If Repair doesn’t help, run it again and choose Install.
4. Add the Ubisoft Anti-Cheat executable to the exclusions list in Windows Security → Virus & threat protection → Manage settings → Exclusions, so security software can’t block it.

A named error such as “Failed to start the driver service” or “Failed to start BattlEye service” has its own walkthrough: Rainbow Six Siege anti-cheat error fix.

Fix 4 — Update Windows and your GPU driver

Ubisoft lists both as standard crash fixes. Install pending (non-preview) Windows updates, then update the graphics driver from AMD, Intel or NVIDIA directly. To see which driver you have, Ubisoft’s guide uses DxDiag:

1. Press Win + R, type dxdiag and press Enter.
2. Open the Display tab and note the driver version.

If crashes started right after a driver update, roll back to the previous version or do a clean install with DDU. Remove any GPU overclock or undervolt while you test, including profiles applied by MSI Afterburner; an overclock that passes other games can still fail in Siege’s DX12 renderer. That last step is our guidance rather than Ubisoft’s.

Fix 5 — Run Siege as administrator

Ubisoft says administrator rights give the game full read and write access, which can help with crashes and freezes. Right-click the launcher you use (Ubisoft Connect, Steam or Epic) → Run as administrator, then start Siege from it. To make it permanent, open the launcher’s Properties → Compatibility tab and tick Run this program as an administrator.

Fix 6 — Close background apps and overlays

Ubisoft’s guide notes that some Microsoft services and third-party programs running in the background interfere with games. Close everything you don’t need before launching: browser, RGB and fan-control utilities, hardware monitors, recording tools and in-game overlays (Discord, Steam, NVIDIA app, Xbox Game Bar). If the crash stops, add them back one at a time to find the conflict.

Fix 7 — Check the system requirements

Ubisoft says that if your PC is below the minimum requirements, that is most likely the cause, and support may not be able to help further. Compare your CPU, GPU and RAM with the requirements on the game’s store page, and make sure you are on 64-bit Windows 10 or 11.

Siege is DirectX 12 only now

Older crash guides tell you to “switch to Vulkan” or “launch with DirectX 11”. Neither works any more. Ubisoft removed Vulkan and then DirectX 11; since Y10S1 (Operation Prep Phase, March 2025) the PC game ships as a single DirectX 12 executable, and old launch options for the other APIs do nothing. A DirectX 12 or “device removed” crash is a driver or GPU-stability problem: work through Fix 4, and see the DXGI_ERROR_DEVICE_HUNG fix or the DXGI_ERROR_DEVICE_REMOVED fix if either error string appears.

Still crashing? Send Ubisoft a report

Ubisoft asks PC players whose problem persists to contact support and attach a DxDiag and an MSInfo report:

1. DxDiag: press Win + R, type dxdiag, wait for it to finish and choose Save All Information.
2. MSInfo: press Win + R, type msinfo32, then File → Export.

You can also log the crash on the Rainbow Six Siege bug reporter: Ubisoft asks for the steps that lead to the bug, what you expected to happen, how to reproduce it, any workaround you found, and screenshots or video.

If it isn’t a crash: stutter and FPS drops

Hitches that don’t close the game are a performance problem. Start with the Rainbow Six Siege stuttering fix, then tune with the best Rainbow Six Siege settings for FPS and the Rainbow Six Siege lowest input lag settings.

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