Software & Apps Windows How to Fix D3dx9_31.dll Not Found or Missing Errors A troubleshooting guide for D3dx9_31.dll errors by Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated on February 20, 2020 Windows The Ultimate Laptop Buying Guide Tweet Share Email All d3dx9_31.dll issues are caused in one way or another by a single issue: a problem with Microsoft DirectX. The d3dx9_31.dll file is one of many files contained in the DirectX software collection. Since DirectX is utilized by most Windows-based games and other advanced graphics programs, d3dx9_31.dll errors usually show up only when using these programs. Any of Microsoft's operating systems since Windows 98 may be affected by d3dx9_31.dll and other DirectX issues. This includes Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, and Windows 2000. D3dx9_31.dll Errors There are a number of different errors involving d3dx9_31.dll, any one of which may show up on your computer. These are just some of the more common DLL error messages you might run into: D3DX9_31.DLL Not FoundD3dx9_31.dll not found. Reinstalling might help fix thisFile d3dx9_31.dll not foundThe file d3dx9_31.dll is missingD3DX9_31.DLL is missing. Replace D3DX9_31.DLL and try againMissing component d3dx9_31.dllThis application has failed to start because d3dx9_31.dll could not be found It's important to understand the context during which the d3dx9_31.dll error occurs in order to properly fix it. For example, you don't want to troubleshoot a missing DLL error for a video game if your error is related to a graphics editing program. The d3dx9_31.dll error message could apply to any program that utilizes Microsoft DirectX, but it's most commonly video games, and it typically appears when the game is started. In non-game applications, a d3dx9_31.dll error might appear when the program starts or before graphics features of the program are used. Some common games and other programs that have been known to generate d3dx9_31.dll errors include Tom Clancy's Rainbow Six, Battlestations: Midway, Vanguard: Saga of Heroes, Supreme Commander, Star Wolves 2, NeonDS (a Nintendo DS emulator), Autodesk Inventor Professional, Hospital Tycoon, Spider-Man 3, Halo 2, Transformers, and more. How to Fix D3dx9_31.dll Errors Do not, under any circumstances, download the d3dx9_31.dll DLL file individually from any DLL download site. There are a number of different reasons that downloading DLLs from these sites is a bad idea. If you've already downloaded d3dx9_31.dll from a DLL download site, remove it from wherever you put it and continue with the following steps. Restart your computer if you haven't already. The d3dx9_31.dll error might be a one-time issue and a simple restart could clear it up completely. It's unlikely this will fix the problem, but restarting is always a good first step with nearly any problem. Install the latest version of Microsoft DirectX. Chances are, upgrading to the latest version of DirectX will fix the d3dx9_31.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, 7, Vista, XP, and more. It will replace any missing DirectX 11, DirectX 10, or DirectX 9 file. Assuming the latest DirectX version from Microsoft doesn't fix the d3dx9_31.dll error you're receiving, look for a DirectX installation program on your game or application CD or DVD. Usually, if a game or another program utilizes DirectX, the software developers will include a copy of DirectX on the installation disc. Sometimes, though not often, the DirectX version included on the disc is a better fit for the program than the latest version available online. Uninstall the game or software program and then reinstall it again. Something might have happened to the files in the program that work with d3dx9_31.dll and a reinstallation could do the trick. Restore the d3dx9_31.dll file from the latest DirectX package. If the above steps haven't worked to resolve your d3dx9_31.dll error, try extracting the d3dx9_31.dll file individually from the DirectX software package. 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 whole lot more.