Multiple assemblies with equivalent identity - System.Runtime.dll - asp.net-core-mvc

Question

I have a MVC6 project with beta-8, when I add the System.Security.Claims nuget package, I’ll get the following compile error:
Error CS1703 Multiple assemblies with equivalent identity have been imported: 'C:\Users\username.dnx\packages\System.Runtime\4.0.20\ref\dotnet\System.Runtime.dll' and 'C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5.1\Facades\System.Runtime.dll'. Remove one of the duplicate references.
Any guidance on fixing this issue will be greatly appreciated!
I was able to replicate from just a simple new project, Beta8Class is just a common class library in the solution, here is the project.json:
{
"webroot": "wwwroot",
"version": "1.0.0-*",
"dependencies": {
"Beta8Class": "1.0.0-*",
"Microsoft.AspNet.Diagnostics": "1.0.0-beta8",
"Microsoft.AspNet.IISPlatformHandler": "1.0.0-beta8",
"Microsoft.AspNet.Mvc": "6.0.0-beta8",
"Microsoft.AspNet.Mvc.TagHelpers": "6.0.0-beta8",
"Microsoft.AspNet.Server.Kestrel": "1.0.0-beta8",
"Microsoft.AspNet.StaticFiles": "1.0.0-beta8",
"Microsoft.AspNet.Tooling.Razor": "1.0.0-beta8",
"Microsoft.Framework.Configuration.Json": "1.0.0-beta8",
"Microsoft.Framework.Logging": "1.0.0-beta8",
"Microsoft.Framework.Logging.Console": "1.0.0-beta8",
"Microsoft.Framework.Logging.Debug": "1.0.0-beta8",
"Microsoft.VisualStudio.Web.BrowserLink.Loader": "14.0.0-beta8",
"System.Security.Claims": "4.0.1-beta-23409"
},
"commands": {
"web": "Microsoft.AspNet.Server.Kestrel"
},
"frameworks": {
"dnx451": { },
"dnxcore50": { }
},
"exclude": [
"wwwroot",
"node_modules"
],
"publishExclude": [
"**.user",
"**.vspscc"
],
"scripts": {
"prepublish": [ "npm install", "bower install", "gulp clean", "gulp min" ]
}
}
Thanks

Answer 1

You get conflicting reference because this is a beta version and mixing two different version will lead to reference conflicts. You should use all beta8 versions.
If you want something with security you can use these packages
"Microsoft.AspNet.Authentication.Cookies": "1.0.0-beta8",
"Microsoft.AspNet.Authentication.Facebook": "1.0.0-beta8",
"Microsoft.AspNet.Authentication.Google": "1.0.0-beta8",
"Microsoft.AspNet.Authentication.MicrosoftAccount": "1.0.0-beta8",
"Microsoft.AspNet.Authentication.Twitter": "1.0.0-beta8",

Answer 2

System.Security.Clamis package version 4.0.1-beta-23409 supports only dnxcore5. Try removing dnx451 target framework.
You may confirm this on NuGet gallery:
https://www.nuget.org/packages/System.Security.Claims/4.0.1-beta-23409
another clue is that your error message says that it searches dotnet folder. I am not yet fully sure how those generator works but this a moniker for core target framework only.