Diagnosing basic problems with DirectX

DirectX is required by many games and multimedia apps in Windows. DirectX is built in to Windows and can't be uninstalled.

If you're having problems getting a game, movie or multimedia app to play properly, the DirectX Diagnostic Tool can help you identify the problem. Here's how to open it.

  1. Swipe in from the right edge of the screen, and then tap Search.
    (If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, and then click Search.)

  2. Enter dxdiag in the search box, and then tap or click dxdiag.


  • If this is the first time you’ve used the DirectX Diagnostic Tool, you might be asked to check if your drivers are digitally signed. We recommend you tap or click Yes to help verify their authenticity. For more info, see How can I decide which drivers are safe to install?

When the diagnostic tool is open, check these items.

Which version of DirectX is on your PC

Some older apps and games require D3DX. If you see an error message such as: "The program can't start because d3dx9_35.dll is missing from your computer. Try reinstalling the program to fix this problem." (The last two digits of the file name might vary.) Go to the DirectX End-User Runtime web Installer webpage and follow the instructions to install DirectX 9, which includes DXD3 support.

Old or unsigned drivers

A driver that is digitally signed has been tested for DirectX compatibility. Tap or click the tabs for whichever hardware is causing the trouble and look for driver problems. Installing the latest driver will often solve the problem. You can typically find the latest driver in the support section of the manufacturer's website.

Your game controller

If a joystick or other input device doesn't respond, it might not be installed correctly. Make sure the device appears in the Input tab. If not, reinstall the device according to the manufacturer's instructions. If it's a USB device, unplug it and then plug it back in. If the controller appears in the Input tab but still doesn’t work, trying installing the latest driver from the support section of the manufacturer's website.

Need more help?