# Unreallightmass.exe - Error 0xc000007b - Unable to Start **URL:** \ **Category:** Platform & Builds\ **Tags:** light, unreal-engine, 0xc000007b, question\ **Created:** [December 21, 2017, 12:37am UTC](https://forums.unrealengine.com/t/unreallightmass-exe-error-0xc000007b-unable-to-start/412792 "2017-12-21T00:37:58Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![BoreamsGames](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@BoreamsGames](https://forums.unrealengine.com/u/BoreamsGames)\ **Post date:** [December 21, 2017, 12:37am UTC](https://forums.unrealengine.com/t/unreallightmass-exe-error-0xc000007b-unable-to-start/412792/1 "2017-12-21T00:37:58Z")
I’ve tried multiple fixes on the internet, including reinstalling VS2013, and using Dwalker, which returned no errors at all. Please respond with a potential fix, as I’m unable to compile lighting at all. please don’t reply with the answer, “Reinstall windows”. Honestly, its a idiotic response, this isn’t an issue with my OS. ---
**Author:** ![BoreamsGames](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@BoreamsGames](https://forums.unrealengine.com/u/BoreamsGames)\ **Post date:** [December 22, 2017, 12:24am UTC](https://forums.unrealengine.com/t/unreallightmass-exe-error-0xc000007b-unable-to-start/412792/2 "2017-12-22T00:24:26Z")
Thanks for nothing… ---
**Author:** ![Jakmilo](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Jakmilo](https://forums.unrealengine.com/u/Jakmilo)\ **Post date:** [January 25, 2018, 9:20am UTC](https://forums.unrealengine.com/t/unreallightmass-exe-error-0xc000007b-unable-to-start/412792/3 "2018-01-25T09:20:44Z")
This worked for me, I downloaded the file [d3dx9\_43.dll free download | DLL‑files.com](https://www.dll-files.com/d3dx9_43.dll.html) and pasted it in the system32 folder, I clicked replace it and it’s ready