Unity3d DllNotFoundException is showing a directory that doesn't exist on my computer

Question

I'm trying to use an asset in my unity project, it has a c# script.cs that calls and initializes the plugins, when the game starts. but when I press the play button, unity keeps throwing DllNotFoundException

this is the picture of the error i get when i play the game (sorry, i had to send a picture and censor some parts, because of the term of use i signed)

the error says

at "C:/Users/thatcompany/source/repos/plugin-name/plugin-name-api/a-class-in-plugin.cs:192"

and this path doesn't even exist on my computer

this asset is for unity3d and is written in c# and c++. the code that is used for initialization is written in c#, it uses a DLL file which is also written in c#, and that DLL file uses another DLL file which is written in c++ and has

[DllImport("DllThatUnityCantFind", EntryPoint = "name_initialize", CharSet = CharSet.Ansi)]
public static extern IntPtr Name_initialize(int argc, string[] argv);

this is the only line of code that I found useful for this question, as the other lines don't even get a chance to get executed.

I've have read all of the related questions on this website and others and tried these answers,

• putting DLL files in the root of the project

• putting DLL files in unity editor main folder

• separating DLL files into different directories

• putting dependant DLL files into the root of the project while having the other one in the plugin folder and visa versa

• switching Scripting Runtime Version to 3.5 and 4.x

• changing API capability Level

• making a new project

• restarting the editor

• opening the unity editor as administrator

• updating unity to the version that this plugin is tested on

• updating unity to the latest version

• changing name of the DLL file to name.dll.dll instead of name.dll

• changing the platform setting of the plugin

• installing all the different versions of VC redist 2005-2019, 32 and 64 bits

• updating to the latest version of .net core and .net framework

The DLL file that unity can't import also shows a warning message

the DLL file that can't be found in unity, in dependency walker

Answer 1

That DLL links against VS 2015 debug runtime (MSVCP140D.dll). Unless Visual Studio 2015 with C++ workload is installed on your machine, the DLL will not load.

This is a bug in the .DLL - DLLs that get distributed should not be compiled against debug C++ runtime. I suggest contacting the person you got this DLL from and ask them to rebuild it in "Release" config. While you're at it, you might also want to ask them to link CRT statically, as otherwise you'll have to have VS 2015 C++ redistributable package installed on the machine you're trying to use that DLL on.