# Copy 3rd Party DLLs to Binaries folder does not work for Engine Plugin - How to solve?

**URL:** <https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255>\
**Category:** Plugins\
**Tags:** dll, Third-Party, Code-Plugins, unreal-engine\
**Created:** [December 29, 2022, 11:54am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255 "2022-12-29T11:54:24Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![Hausfrau8787](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Hausfrau8787](https://forums.unrealengine.com/u/Hausfrau8787)\
**Post date:** [December 29, 2022, 11:54am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/1 "2022-12-29T11:54:24Z")

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Hey everyone!

I’m struggling with a very strange problem and I already tried out everything that I could imagine but still the problem persists and I hope that you guys can help me.

I built a code plugin that uses some Third-Party DLLs. It works perfectly as a project plugin and copies over the needed DLLs to the Binary folder using

```auto
            RuntimeDependencies.Add("$(BinaryOutputDir)/depthengine_2_0.dll", depthEngineDllPath);
            RuntimeDependencies.Add("$(BinaryOutputDir)/k4a.dll", k4aDllPath);
            RuntimeDependencies.Add("$(BinaryOutputDir)/k4abt.dll", k4abtDllPath);

```

However, as an engine plugin on the UE Marketplace, this does not work anymore. I already tried out multiple things, e.g.:

```auto
            RuntimeDependencies.Add("$(TargetOutputDir)/depthengine_2_0.dll", depthEngineDllPath);
            RuntimeDependencies.Add("$(TargetOutputDir)/k4a.dll", k4aDllPath);
            RuntimeDependencies.Add("$(TargetOutputDir)/k4abt.dll", k4abtDllPath);

            RuntimeDependencies.Add("$(PluginDir)/Binaries/Win64/depthengine_2_0.dll", depthEngineDllPath);
            RuntimeDependencies.Add("$(PluginDir)/Binaries/Win64/k4a.dll", k4aDllPath);
            RuntimeDependencies.Add("$(PluginDir)/Binaries/Win64/k4abt.dll", k4abtDllPath);

```

But still the DLLs are not copied over. I am pretty sure that the paths (k4aDllPath etc.) are correct:

```auto
string sdkPath = Path.GetFullPath(Path.Combine(PluginDirectory, "Source/ThirdParty/azure-kinect-sdk"));
string k4aDllPath = Path.Combine(sdkPath, "sdk", "windows-desktop", "amd64", "release", "bin", "k4a.dll");

```

What am I missing? Or how can I debug this problem best?

I really hope that you guys can help me and I’m looking forward to any helpful answer!!

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**Author:** ![Hausfrau8787](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Hausfrau8787](https://forums.unrealengine.com/u/Hausfrau8787)\
**Post date:** [January 5, 2023, 8:12am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/2 "2023-01-05T08:12:42Z")

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Anyone?? 😕

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**Author:** ![kalmiya](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kalmiya](https://forums.unrealengine.com/u/kalmiya)\
**Post date:** [May 26, 2023, 2:22pm UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/3 "2023-05-26T14:22:25Z")

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Hey there, coincidentally found your post after messing with RuntimeDependencies.Add for a few hours. I’m not doing anything with the marketplace, but since I spent an unreasonable amount of time messing around thought I’d share my experience.

Having a 3rdparty library with a DLL and wanted it to be copied over. Documentation states to use $(TargetOutputDir) but the file doesn’t appear where my executable is in \Binaries\Win64. It certainly doesn’t do what I expect it to do, maybe it does copy it to some unexpected location - no clue.

Eventually tried $(PluginDir) and that worked copying the dll to the folder with the .build.cs file, as expected (still the wrong location, but at least something was copied - so I could at least rule out that the source path was wrong).

Then tried $(BinaryOutputDir) and with that the file does land next to the executable in \Binaries\Win64. I’m still a bit hesitant about using $(BinaryOutputDir) instead of $(TargetOutputDir), but so far it does what it’s supposed to do.

As a hack, you could copy it in the target.cs file in the postbuild step. I dislike that approach, but depending on how desperate you are it might be worth a try:

```
private void ImplPostBuildCopy(string SrcPath, string DestPath)
{
    PostBuildSteps.Add(string.Format("echo Copying {0} to {1}", SrcPath, DestPath));
    PostBuildSteps.Add(string.Format("xcopy /y /i /v \"{0}\" \"{1}\" 1>nul", SrcPath, DestPath));
}

```

and call it with

> ImplPostBuildCopy(“$(ProjectDir)\source\Plugins\xxx\sdk\bin\win64\yyy.dll”, “$(ProjectDir)\Binaries\$(TargetPlatform)\”);

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<div class="post-metadata">

**Author:** ![sheen](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@sheen](https://forums.unrealengine.com/u/sheen)\
**Post date:** [June 22, 2025, 6:59am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/4 "2025-06-22T06:59:52Z")

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Same problem here

with Package plugin from editor, all RuntimeDependencies are staged correctly.

**when BuildPlugin with RunUAT.bat, the RuntimeDependencies are not staged as Unreal documentation**

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<div class="post-metadata">

**Author:** ![mikel\_iconic](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@mikel\_iconic](https://forums.unrealengine.com/u/mikel_iconic)\
**Post date:** [July 14, 2025, 4:31pm UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/5 "2025-07-14T16:31:48Z")

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Same issue here. If anyone ever figures out how this is supposed to be done, please let us know!

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<div class="post-metadata">

**Author:** ![sheen](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@sheen](https://forums.unrealengine.com/u/sheen)\
**Post date:** [July 23, 2025, 5:54am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/6 "2025-07-23T05:54:14Z")

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For anyone is confusing with this issue you mistake the process of packing Plugin and packing Game.

when you build your plugin with

```bat
RunUAT.bat BuildPlugin 

```

It won’t stage the _RuntimeDependencies_ for you, you need to do this by either

- 
  1. puting the ThirdParty files at correct location where you refer them in your Build.cs file (for example **YourPlugin/Binaries/ThirdParty/…** )  
OR

- 
  1. running some PreBuildSteps scripts to copy them to the correct location where you refer them in your Build.cs (for eamxple copy them from **YourPlugin/Source/ThirdParty/…** to **YourPlugin/Binaries/ThirdParty/…** )

But if you choose to put them directly in **YourPlugin/Binaries/ThirdParty/…** , you cannot submit your plugin package because this is violation against the [(Fab) Technical Requirements - 4.3.7.3.d](https://support.fab.com/s/article/FAB-TECHNICAL-REQUIREMENTS?language=en_US) which states

> Third-party dependencies may only be used with proof of permission and must be placed in a ThirdParty folder located inside the Source folder.

So the correct and available approach is 2.

- Put your ThirdPatry files in **YourPlugin/Source/ThirdParty/…**

- Add PreBuildSteps in your plugin description file **YourPlugin.uplugin** , here is an example

What important to know about how FAB will process your submission:

- The PreBuildSteps scripts will be executed when you build your plugin or build the game project which consumes your plugin.
- ⚠ ⚠_ **DO NOT USE XCOPY ON WINDOWS PLATFORM** _, because it won’t be executed correctly due to the output redirection, use robocopy instead!
- When you submit your plugin package, FAB only need you to provide all source content, any built artifacts are not needed and should not be included in your submission package.
- When FAB gets your plugin package (actually a source package), they will build your plugin with RunUAT.bat or RunUAT.sh with _BuildPlugin_ parameter for all declared supported platforms.
- You need to make sure the folder **YourPlugin/Binaries/ThirdParty/…** will be preserved after the building process by declaring the path in **YourPlugin/Config/FilterPlugin.ini** like:

```ini
[FilterPlugin]
; This section lists additional files which will be packaged along with your plugin. 
; Paths should be listed relative to the root plugin directory, 
; and may include "...", "*", and "?" wildcards to match directories, files, and individual characters respectively.
;
; Examples:
; /README.txt
; /Extras/...
; /Binaries/ThirdParty/*.dll

; Preserver ThirdParty folder
/Binaries/ThirdParty/...

```

- After all platforms were built successfully, FAB will combine all the artifacts in to single one archive file, and they will deploy the archive to the FAB market server. (actually the Intermediate folder will be included because it contains the precompiled files reference, this is important to the project using your plugin)

There is so few documents to describe the FAB build and deploy process, I figure this out by submitting my plugin more than 200 times and eventually published my product successfully.

Hope this will help all developers working on plugins with third-party references.

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<div class="post-metadata">

**Author:** ![Nebiros777](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Nebiros777](https://forums.unrealengine.com/u/Nebiros777)\
**Post date:** [April 3, 2026, 8:45am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/7 "2026-04-03T08:45:14Z")

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Hi Sheen! One big question: where can I get these DLLs, which are missing? Should I build a plugin as a different step?

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<div class="post-metadata">

**Author:** ![sheen](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@sheen](https://forums.unrealengine.com/u/sheen)\
**Post date:** [June 1, 2026, 2:51am UTC](https://forums.unrealengine.com/t/copy-3rd-party-dlls-to-binaries-folder-does-not-work-for-engine-plugin-how-to-solve/738255/8 "2026-06-01T02:51:58Z")

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Hi **[Nebiros](https://dev.epicgames.com/community/api/user_profiles/tab-redirect/about?discourse_username=Nebiros777), sorry for missing your question, but what do you mean the _missing DLLs_?**