How to Fix D3dx9_40.dll Not Found or Missing Errors

A troubleshooting guide for d3dx9_40.dll errors

D3dx9_40.dll problems source from an error with Microsoft DirectX. This DLL file is one of many contained in the DirectX software collection. Since the software is used by most Windows-based games and advanced graphics programs, d3dx9_40.dll errors usually show up only when using these programs.

Any of Microsoft's operating systems since Windows 98 might be affected by d3dx9_40.dll and other DirectX problems. This includes Windows 10, Windows 8, etc.

D3dx9_40.dll Errors

D3dx9_40.dll was not found error message

There are several ways that d3dx9_40.dll errors can reveal themselves on your computer. Here are several of the more common messages:

  • D3DX9_40.DLL Not Found
  • The file d3dx9_40.dll is missing
  • File d3dx9_40.dll not found
  • The program can't start because d3dx9_40.dll is missing from your computer. Try reinstalling the program to fix this problem.
  • D3dx9_40.dll not found. Reinstalling might help fix this.
  • The code execution cannot proceed because d3dx9_40.dll was not found.

The error message could apply to any program that uses Microsoft DirectX, but it's most commonly seen in video games, including Need for Speed, Gothic, Total War, and Psychonauts.

How to Fix D3dx9_40.dll Errors

Do not download d3dx9_40.dll individually from any "DLL download site." Doing so is never a good idea, for multiple reasons. If you already have, remove it immediately from wherever you put it and continue with these steps.

  1. Restart your computer if you haven't yet. The d3dx9_40.dll error might be a fluke and a simple restart could clear it up completely.

  2. Install the latest version of Microsoft DirectX. Chances are, this will fix the "d3dx9_40.dll not found" error.

    Microsoft often releases updates to DirectX without updating the version number or letter, so be sure to install the latest release even if your version is technically the same.

    The same DirectX installation program works with all versions of Windows including Windows 10, 8, etc. It will replace any missing DirectX 11, DirectX 10, or DirectX 9 file.

  3. Assuming the latest DirectX version from Microsoft doesn't fix the error, look for a DirectX installation program on your game or application CD or DVD. Sometimes, though not often, the DirectX version included on the disc is a better fit for the program than the latest version available online.

    Usually, if a game or​ another program uses DirectX, the software developers will include a copy of DirectX on the installation disc. For example, if you're using the game with Steam, it's probably called DXSETUP.exe, and can be found in a redist folder in the game's installation directory. If you can't find it manually, try searching your entire computer for "dxsetup.exe" using a file search tool like Everything.

    Another example is the GB-ASManager program. When the DLL error is seen there, reinstall the software included on the associated DVD.

  4. Uninstall and then reinstall the game or software program. Something might have happened to the files in the program that work with d3dx9_40.dll, and a reinstall could do the trick.

  5. Restore the d3dx9_40.dll file from the latest DirectX package. If the above troubleshooting steps haven't worked to solve your d3dx9_40.dll error, try extracting the file individually from the DirectX package.

  6. Update the drivers for your video card. While it's not the most common solution, in some situations updating the drivers for the video card in your computer could correct this DirectX issue.

Need More Help?

If you're not interested in fixing this problem yourself, see How Do I Get My Computer Fixed? for a full list of your support options, plus help with everything along the way like figuring out repair costs, getting your files off, choosing a repair service, and a lot more.

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