This article will focus on the d3dx9_39.dll error encountered on League of Legends when the OS has recently been reinstalled or updated. Let’s take a look at the many possible fixes for this error.
Install the missing file.
The first way you can approach this error is by downloading the file in question. Open up your browser and go to this site, where you can download missing DLL files for free. Now, scroll down and type into the search bar, d3dx9_39.dll, the name of the file you need. You will find the file on the site. Click on it to download and install it. You will want to download both the 32-bit and the 64-bit versions, since you may require both for other games and software. Next, extract the two zip files you downloaded. The 32-bit file you will be pasting in the System32 folder, found under the Windows folder in your C drive. The 64-bit file will be pasted in the SysWOW64 folder, which is also in the Windows folder of the C drive. Open up League of Legends and see if the d3dx9_39 error is still thrown.
Download DirectX on your device.
The other method to fix this error is to download DirectX by Microsoft. Use this link. Do not worry about any warnings, since DirectX is a verified software from Microsoft. Once the download is complete, install it and you should be all set to get back to LoL!
Use your old windows file to fix it.
The last and most intuitive method to fix this error is by using the older version of Windows to obtain the d3dx9_39.dll file. Simple open up your C drive, and then the Windows.old folder. Open System32 and search for the d3dx9_39.dll file. Simply copy and paste it from here to your regular Windows folder’s System32. Next, do the same with the Windows.old SysWOW64 file, and paste the DLL file to your Windows SysWOW64.
