How to Fix Modern Warfare Direct X Error “DEV ERROR 6456”

This resolution aims to resolve this issue by switching from DirectX 12 to DirectX 11. Why DX11? You may or may not need to do this which you will see later. If you’re having an issue with Discord or the game not launching in Full screen mode this is also covered in this post. DX11 issues are also covered.

This post assumes that you’ve already run “dxdiag” and checked for directx errors and this issue is still happening. It also assumes that you’ve checked for updates for your graphics card drivers, installed your monitor driver (device manager should show the manufacturer and model of your monitor instead of “generic pnp monitor“), and that you have already ran the scan and repair on the game installation.

If you don’t know what model your monitor is and you’re like me and too lazy to move it and look at the sticker or if you have a sticker that is unreadable or missing you can use this guide to use powershell to determine what monitor that you have

It also assumes that you have set your GSync or FreeSync settings to OFF and that you have incrementally enabled those settings as you have launched the game each time you made a change to confirm that wasn’t the cause. Game graphics settings should also be set to default. It also assumes that you have reset your monitor to its factory defaults. You will need to use the monitor menu to do this and it is not accessible with your keyboard and mouse. Also please note that if you are using either of GSync or FreeSync to turn off VSync.

Another assumption is that you don’t have a CPU bottleneck. An easy way to check this is with this web service to determine if you have one. Don’t worry about a GPU bottleneck as that just means you can comfortably upgrade your graphics card from whatever you have up to what the CPU can handle. If you want to know more about a GPU vs CPU bottleneck click here:

You can switch back and forth between each DirectX version to test out if that is what is causing this error as well by uncheckmarking the checkbox that we are about to enable. After checking or unchecking always run the scan and repair tool.

Now that we have that out of the way you can use DX11 as an alternative resolution if none of the above troubleshooting worked. Especially, for older hardware or for those still running on Windows 7.

Why DirectX 11? What’s the difference? Stack Exchange can explain:

As a gamer it doesn’t mean too much. The most obvious difference that DirectX 12 requires Windows 10, while DirectX 11 requires Windows 7 or later. DirectX 12 also requires that your video card driver supports it as well. This means you need to have a relatively recent AMD, NVIDIA or Intel video card with updated drivers.

In terms of its effect on games DirectX 12 doesn’t really change what can be displayed, it just allows for more efficient rendering. Its main improvement is that it lets more than one CPU core to submit commands to the graphic card at the same time. With DirectX 11 or earlier games were effectively limited to accessing the video card from only one CPU core of a multicore CPU at a time.

However the advantages of DirectX 12 aren’t easy for developers to exploit in practice. At this point, I don’t expect that many games will be able make effective use of it. For the most part, only AAA games would have both the resources and the need to usefully exploit DirectX 12.

Since DirectX 12 doesn’t really add new rendering functionality, it just changes the how games access the video card, it’s possible to support it with older hardware simply by updating the drivers.

(To be a bit more technical, Direct3D 12 requires that the driver be updated to use WDDM 2.0 and that the hardware supports at least feature level 11_0. The newer feature levels 12_0 and 12_1, mostly affect how games can access graphics resources. The limited additional hardware requirements meant that some older “DirectX 11” hardware was able to support the newer 12_0 level.)” –

If you prefer a video I made one here:

Otherwise, you can use these steps:

Go to Game Settings in Blizzard launcher

Enter “-d3d11” into additional command arguments text field.

Run the scan and repair tool

If asked to run in safe mode click “Yes”

Fix resolution to match your screen. For now make them match and make sure that the game is working properly. After which you can increase the rendering above what your display puts out such that a more detailed render can be squeezed into your current resolution improving the picture quality. But for now, make them the same.

Click “Advanced” then your screen resolution. Then click Apply.

In my case the screen would go occasionally complete black and then would show up again. (Using AMD RX 580).

Don’t customize your graphics settings just yet.

Then, I recommend restarting the “shaders installation”.

You will then see a notification that the shaders are installing at the top of your screen.

If you can’t edit the graphics settings you can press the keyboard shortcut “Alt + Enter” to enter windowed mode. This will allow you to click on the graphics settings.

Now, each set of settings is tied to a window mode (full screen, windowed, etc.) After getting in to the graphics settings press (Alt + Enter) again to re-enter full screen mode assuming that you want to play in full screen mode.

Now customize your graphics settings keeping an eye on your VRAM usage.

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Hopefully, you will see a nice high quality image on the main menu screen.

Game Not Starting in Full Screen Mode

For me this was annoying each time I launched the game it would start back up in Fullscreen Borderless which would make all of my settings disappear. There is a way that you can force the game to launch into full screen each time. You can do this by adding the “Fullscreen” flag to the game.

There are a few flag options:

  • w (Used for full screen) – This is the one we want
  • window (windowed)
  • windowmode (another windowed mode)

Open your blizzard launcher and click on the game settings again:

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Then enter the “-w” flag. If using in combination with the DirectX11 option it will be “-d3d11 -w”.

When you launch the game the first time it will go into full screen but you will have to configure your graphics settings first. Then to test it close out of the game and relaunch it from the launcher.

Discord Issues during Game

Some people have indicated that they are having issues with Discord during the game. To fix this the launcher needs to close when the game is running. To fix this change this setting:

Set to When launching a game “Exit completely”

As you increase the quality of your image you will notice that your FPS will drop. Find a happy medium from the max settings that your card can handle and a smoothness of play that you’re comfortable with for you FPS to sit at. I find that I’m happy with 60 FPS. If you are doing tournament play and performance is more important that picture quality you can use these settings for a good enough picture quality but without sacrificing FPS.

Still having the Discord Hook 64 Error?

Fully quit Discord. Clicking the X? It’s still running. Click on the “overflow” button in your taskbar. It looks like a caret “^” Find the Discord icon. Right-click and click “Quit”.

Then go ahead and launch the game. Go through any of the previous steps mentioned. After your graphics are fixed it’s time to relaunch Discord. Press “alt+tab” to keep Modern Warfare open but return to your desktop. Then Open Discord.



  • Display Mode: Fullscreen
  • Render Resolution: 100
  • Screen Refresh Rate: Maximum for your monitor (60/144/240)
  • Aspect Ratio: Automatic
  • V-sync: Disabled
  • Custom Framerate Limit: Unlimited
  • Nvidia Highlights: Disabled


  • Texture Resolution: Low
  • Texture Anisotropic Filtering: Normal
  • Particle Quality: High
  • Bullet Impacts and Sprays: Disabled
  • Tesselation: Disabled

Shadows & Lighting

  • Shadow Map Resolution: Low
  • Cache Spot Shadows: Enabled
  • Cache Sun Shadows: Enabled
  • Particle Lighting: Normal
  • Direct X Raytracing: Disabled
  • Ambient Occlusion: Disabled
  • Screen Space Reflection: Disabled

Post Processing Effects

BEST Picture Quality

As mentioned previously if you’re running DX11 and experience an error you can flip it by disabling the checkbox which will cause the game to launch natively in DX12. You may optionally decide to keep it on while removing the “-d3d11” flag but keeping the full screen flag “-w” in the text field.

Safe mode dialogue box:

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This will force reset the game to DX12 and if you still want to force it to open with full screen just leave it checked with only the “-w” flag in the text field.

If you had this error:

Error code: 0x000000b 104270004 7610867 0xc0000005

Check this post:

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