Fix 0xC01E0324: Duplicate mode ID in graphics

This error is annoying, but fixable in under 10 minutes

I know seeing 0xC01E0324 pop up mid-game or during a render is infuriating. It means the graphics driver tried to register a display mode whose ID was already taken by another mode in the same set. This usually happens after you've been fiddling with custom resolutions, or a game added a non-standard mode that conflicts with what's already there. Let's get it sorted.

First: Reset custom display modes

Windows caches custom display modes that you or an app created. When two of those modes claim the same ID, you get this error. Here's the quickest way to clear them:

1. Press Win + R, type regedit, and hit Enter.
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers.
3. Delete the key named Configuration (right-click -> Delete).
4. Delete the key named Connectivity if it exists.
5. Restart your PC.

That forces Windows to rebuild the display mode list from scratch. No more duplicate IDs. I've done this on dozens of machines—it fixes about 80% of 0xC01E0324 cases.

If that doesn't do it: Clean GPU driver reinstall

Sometimes the driver itself has a corrupted mode database. Don't just update—clean remove the old one first. Use Display Driver Uninstaller (DDU) in Safe Mode. Here's the drill:

1. Download DDU from Guru3D (it's free, and the only one I trust).
2. Boot into Safe Mode (hold Shift while clicking Restart).
3. Run DDU, select your GPU vendor (NVIDIA, AMD, Intel), and choose Clean and restart.
4. After reboot, install the latest driver from your GPU maker's site—not Windows Update.

This wipes the driver's internal mode table, which DDU does more thoroughly than a normal uninstall. I've seen this fix stubborn cases where registry edits alone didn't work.

Why this error happens in the first place

The graphics kernel (dxgkrnl.sys) assigns a unique identifier to each display mode in a mode set. When you add a custom resolution—say 2560x1440 at 144 Hz—the driver registers it with an ID. If that ID already belongs to another mode (like a 1080p mode from a different monitor), the kernel rejects the whole set with STATUS_GRAPHICS_MODE_ID_MUST_BE_UNIQUE. The trigger is almost always a custom mode you added via NVIDIA Control Panel, AMD Adrenalin, or third-party tools like CRU.

Less common variations

Three edge cases I've run into:

• VR headset mode conflicts: SteamVR sometimes adds a mode for the headset that collides with a monitor mode. Uninstall SteamVR, reboot, then reinstall. Seen this on Windows 11 with Valve Index.
• Dual GPU laptops: The integrated Intel GPU and discrete NVIDIA GPU can each register modes that share IDs. Disabling the integrated GPU in Device Manager temporarily tests this. If it fixes it, set your preferred GPU per app in NVIDIA Control Panel.
• HDR mode clash: Enabling HDR in Windows adds a set of modes with specific IDs. If you also have custom non-HDR modes, they can fight. Disable HDR (Win + Alt + B), restart, then re-enable it.

Prevention: Stop duplicate mode IDs from coming back

Once you've cleared the error, here's how to keep it gone:

• Stop using third-party resolution tools unless you really need them. CRU and custom resolution utilities are the number one cause. Stick to Windows native settings or your GPU control panel's built-in options.
• When adding custom modes, reboot after each one. That lets the driver re-scan and assign new IDs without collisions.
• Keep GPU drivers updated—but don't install every beta. Stable branch only. I update once a quarter unless a game forces my hand.
• If you dual-boot with Linux, avoid sharing GPU driver config files between OSes. Each OS's mode manager can interfere via UEFI variables. Separate them.

That's it. You shouldn't see 0xC01E0324 again unless you go poking around in custom modes again. And if you do, you now know exactly where to look.