I can't seem to get HttpClient to be recognized in Unity 2018.1.0f2. I tried in both standalone & Android target platforms with the following settings: Scripting Runtime version: .NET 4.x equivalent Scripting Backend: Mono Api Compatibility Level: .NET 4.x Based on other forum posts, I added an mcs.rsp file to the root of the Assets folder with the following in it: -r:System.Net.Http.dll I tried clearing all generated folders (Library, etc.), restarting Unity, nothing works. Unity simply refuses to see the System.Net.Http namespace. What am I missing here?