d3dx9_43.dll Is Missing? Install the DirectX End-User Runtime

An older game fails to start with “The program can’t start because d3dx9_43.dll is missing from your computer” (or a similar d3dx9_*, d3dx10_*, d3dx11_*, XINPUT1_3.dll, or XAudio2_7.dll file).

Why: These are legacy DirectX SDK libraries (D3DX9/10/11, XInput 1.3, XAudio 2.7, XACT). Modern Windows ships the current DirectX runtime but not these older side-by-side components, so games built against them can’t find the DLL. Microsoft’s DirectX End-User Runtime installs them — it doesn’t change your DirectX version, it just adds the legacy pieces.

Fix 1: Install the DirectX End-User Runtime

1. Download the DirectX End-User Runtime Web Installer from Microsoft’s official Download Center: https://www.microsoft.com/en-us/download/details.aspx?id=35
2. Run the downloaded dxwebsetup.exe, accept the terms, and let it install. It pulls the legacy D3DX9/10/11, XInput 1.3, XAudio 2.7, and XACT libraries.
3. Reboot and launch the game again.

This is the supported fix — it installs the exact d3dx9_43.dll and related files that older games expect.

Fix 2: Use the offline package if the web installer fails

If the web installer can’t download (no internet on that PC, or a corporate proxy blocks it), use the full offline bundle:

1. Download DirectX End-User Runtimes (June 2010) from the Microsoft Download Center: https://www.microsoft.com/en-us/download/details.aspx?id=8109
2. Run the .exe — it extracts files to a folder you choose; it does not install yet.
3. Open that folder and run DXSETUP.exe to actually install the runtime.
4. Reboot and retry the game.

Fix 3: Reinstall the game

If the error persists for one title only, its bundled DirectX redist may not have run. Uninstall the game, reboot, and reinstall it from the original installer — most game setups include and run the DirectX runtime during installation.

FAQ

Will this downgrade my DirectX 12? No. The End-User Runtime only adds optional legacy side-by-side libraries; it doesn’t touch the DirectX version built into Windows.

Can I just download d3dx9_43.dll from a DLL site? Don’t — a single lifted DLL is unsupported and risky, and these files are designed to be installed as a registered set. Use Microsoft’s runtime installer.

XINPUT1_3.dll or XAudio2_7.dll is missing instead — same fix? Yes. Those ship in the same DirectX End-User Runtime, so Fix 1 covers them too.

Sources: Microsoft Download Center — DirectX End-User Runtime Web Installer · Microsoft Download Center — DirectX End-User Runtimes (June 2010)