Importing DLL Assembly 'dll' will not be loaded due to errors:

Unity Engine
1

Hello, so Im trying to use an external DLL with Unity. I have tested it in a visual studio project and it works fine, my problem is when I try to use it with Unity.

As far as I know you need to import you DLL inside your asset folder. I did that and also changeg the API compatibility level to 4.X. Also removed text mesh pro because it was giving me errors with the dll.

My problem its that I get in the console

Assembly 'Assets/Plugins/OzekiSDK.dll' will not be loaded due to errors:
Unable to resolve reference 'PresentationFramework'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.
Unable to resolve reference 'PresentationCore'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.
Unable to resolve reference 'Ozeki.Libs.BouncyCastle'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.
Unable to resolve reference 'System.Speech'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.
Unable to resolve reference 'WindowsFormsIntegration'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.

I dont know how can I fix it or reference the dll like in a visual project, adding it and using it.
Tried with Unity 2017 and didnt work. Currently using 2018 LTS

The dll that im trying to use its Ozoki SDK, last version.

2

I am getting a similar issue.
Assembly ‘mytest.dll’ will not be loaded due to errors:
Unable to resolve reference ‘PresentationFramework’. Is the assembly missing or incompatible with the current platform?

Now, I have another dll with the same reference that does work. My issue is why does one dll work but not the other.

3

I have been trying to figure this out for the last few days and I believe I found to reason for issue. PresentationFramework and PresentationCore are both .Net Framework APIs. Unity implements the .Net Standard. Here is what I found about that.

“Starting with .NET Standard 2.0, the .NET Framework compatibility mode was introduced. This compatibility mode allows .NET Standard and .NET Core projects to reference .NET Framework libraries. Referencing .NET Framework libraries doesn’t work for all projects, such as if the library uses Windows Presentation Foundation (WPF) APIs, but it does unblock many porting scenarios.”

Ozeki.Libs.BouncyCastle might use .Net Framework APIs that do not work with the .Net Standard. You might try to get the library you need .Net standard compliant if you have access to the source or can contact the owner. If you cannot then you will need to a different library or create your own. I hope this helps.