:( Oops. 500 Internal Server Error - An error occurred while starting the application.

I have created .net core web api application. When I start my .net core application I'm getting ":( Oops. 500 Internal Server Error - An error occurred while starting the application." error on the web page. Previously it's working fine but when I added "net462" instead of "netcoreapp1.0" into the project.json file it's occurred. Could you please let me know if anyone knows this issue?

Project.json

{"dependencies": {
    //"Microsoft.NETCore.App": {
    //  "version": "1.0.1",
    //  "type": "platform"
    //},"Microsoft.AspNetCore.Mvc": "1.0.1","Microsoft.AspNetCore.Routing": "1.0.1","Microsoft.AspNetCore.Server.IISIntegration": "1.0.0","Microsoft.AspNetCore.Server.Kestrel": "1.0.1","Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0","Microsoft.Extensions.Configuration.FileExtensions": "1.0.0","Microsoft.Extensions.Configuration.Json": "1.0.0","Microsoft.Extensions.Logging": "1.0.0","Microsoft.Extensions.Logging.Console": "1.0.0","Microsoft.Extensions.Logging.Debug": "1.0.0","Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0","IdentityModel": "2.0.0","Microsoft.AspNetCore.Diagnostics": "1.0.0","Microsoft.AspNetCore.Cors": "1.1.0","Newtonsoft.Json": "9.0.1","JsonWebTokens": "1.3.0","jose-jwt": "2.1.0","IdentityServer.DAL": "1.0.0-*","Microsoft.AspNetCore.Mvc.WebApiCompatShim": "1.0.1","System.IdentityModel.Tokens.Jwt": "5.1.3","Microsoft.IdentityModel.Protocols": "2.1.0","Microsoft.AspNetCore.Authentication.JwtBearer": "1.0.0","BouncyCastle.NetCore": "1.8.1.2","Sendgrid": "9.0.12","RollbarDotNet": "0.5.1","Microsoft.ApplicationInsights.AspNetCore": "1.0.2","IDAM.Sync": "1.0.0-*","Nse.ServiceBus.DataContracts": "1.8.0.350"
  },"tools": {"Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
  },"frameworks": {"net462": {}
  },
  //"frameworks": {
  //  "netcoreapp1.0": {
  //    "imports": [
  //      "dotnet5.6",
  //      "portable-net45+win8"
  //    ]
  //  }
  //},"buildOptions": {"emitEntryPoint": true,"preserveCompilationContext": true
  },"runtimeOptions": {"configProperties": {"System.GC.Server": true
    }
  },"publishOptions": {"include": ["wwwroot","appsettings.json","web.config","nse.p12"
    ]
  },"scripts": {"postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  }
}