The D3dx9_30.dll missing error usually pops up in ‘multimedia rich’ applications and I can point two important points of failure that cause this error to erupt. In the following guide you’ll find two ways that’ll enable you to get rid of this error and keep using those applications that are using this file with no problems.
This file was created by Microsoft. It is part of your Windows OS as well as part of Microsoft’s DirectX technology. DirectX technology enhances and improves the display of graphics, sound, and other multimedia components. This technology mainly supports ‘multimedia rich’ applications such as PC games. This specific file can usually be located at your C:\Windows\System32 folder.
You’d usually encounter errors with this file while trying to unsuccessfully launch a game or other graphic software. Windows usually pops up an error message saying that The dynamic link library d3dx9_30.dll could not be found in the specified path, or that it is missing from your computer or it could not be loaded, or This application has failed to start because d3dx9_30.dll was not found.
Causes to this dll error
From some reason Windows can’t find that dll module on your PC, or at least it says that it can’t find it although it might exist on your PC. This can happen in the following situations:
(1) File has been accidently deleted from your PC
(2) You’re using an old/incompatible version of this file that Windows rejects
(3) You’re using an old/incompatible graphic card or sound card driver, or other multimedia related driver.
(1) Install the latest DirectX 9.0 version
This file belongs to DirectX 9.0, so simply download and install the latest version of DirectX 9.0 (latest DirectX installation).
(2) Update all your Multimedia related drivers
Another common reason for the D3dx9_30.dll missing error - one or several of your Multimedia related drivers is either incompatible or too old (might be corrupt as well). You need to detect incompatible or missing drivers and replace them with their most updated (official) versions.
Here is an easy way to detect and replace those drivers:
(1) Download this drivers scanner
(2) Let it scan all your installed drivers
(3) By the end of the scan open the Drivers section
(4) See which drivers require an update
(5) Replace those drivers
(6) Restart your PC
Following these two steps should fix the D3dx9_30.dll missing error and most other errors related to this file.