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Common problemRainbow SixWindows PC
Rainbow Six Siege won't launch
Ubisoft Anti-Cheat damaged or blocked
Siege uses Ubisoft Anti-Cheat, and the game can fail to start when the anti-cheat install is damaged, game files are missing, or security software blocks it.
How to fix it
Verify the game files in Ubisoft Connect, Steam or the Epic Games Launcher.
Open the Sentinel folder inside the game's install folder.
Run UbisoftAntiCheatInstaller.exe as administrator and choose Repair.
If that fails, run it again and choose Install.
Add the Ubisoft Anti-Cheat .exe to the exclusions list in Windows Security.
From Rainbow Six's help pages: ubisoft.com, in our words. Checked on 11 November 2026. If the steps do not help, Rainbow Six's own support is the next stop.
More Rainbow Six errors and common problems
- Can't connect to serversOutage, router or software conflict
- Game crashes or stuttersOld drivers, damaged files or background apps
- High pingGame picked a far away data centre
- Legend Division lockedPC security features are not turned on
- 3-0x0001000BConnection to the server was lost
- 2-0x0000D00AMatchmaking service connection dropped
- Failed to load player profileLocal save file is corrupted
- 0-0x00000312Connection through your provider was lost
- 6-0x00001000Matchmaking service connection dropped
- 0-0x00001001Lost the connection to BattlEye
- 2-0x0000C015Connection to the server was lost
- 01102Secure Boot not set up correctly
All Rainbow Six errors and common problemsLive Rainbow Six status