title: .NET core 3.0 get Invalid runtimeconfig.json when starting console application
body: <p>We are building a larger solution with .net core 3.0 and C#, where one of the projects is a console application that outputs an exe. I just recently started working on it, but cant get it to run. When I start it in debug mode in Visual Studio (2019, version 16.3.10, running on Windows 10), I get this message:</p>
  
  <pre class="lang-none prettyprint-override"><code>Invalid runtimeconfig.json [C:\loong-path\projectname\bin\Debug\netcoreapp3.0\projectname.runtimeconfig.json] [C:\loong-path\projectname\bin\Debug\netcoreapp3.0\projectname.runtimeconfig.dev.json]
  C:\loong-path\projectname\bin\Debug\netcoreapp3.0\projectname.exe (process 3312) exited with code -2147450733.
  To automatically close the console when debugging stops, enable Tools-&gt;Options-&gt;Debugging-&gt;Automatically close the console when debugging stops.
  Press any key to close this window . . .
  </code></pre>
  
  <p>When looking at the <code>runtimeconfig.json</code> it seems to be really simple, and correct:</p>
  
  <pre class="lang-json prettyprint-override"><code>{
    "runtimeOptions": {
      "tfm": "netcoreapp3.0",
      "framework": {
        "name": "Microsoft.NETCore.App",
        "version": "3.0.0"
      }
    }
  }
  </code></pre>
  
  <p>And the same goes for the <code>runtimeconfig.dev.json</code>:</p>
  
  <pre class="lang-json prettyprint-override"><code>{
    "runtimeOptions": {
      "additionalProbingPaths": [
        "C:\\Users\\myusername\\.dotnet\\store\\|arch|\\|tfm|",
        "C:\\Users\\myusername\\.nuget\\packages",
        "C:\\Program Files\\dotnet\\sdk\\NuGetFallbackFolder"
      ]
    }
  }
  </code></pre>
  
  <p>I've tried cleaning before building, and deleting the bin folder before building, but the <code>runtimeconfig.json</code> gets regenerated and looks the same.</p>
  
  <p>I've tries running it with dotnet from the console, but get basically the same output as from Visual Studio. Even when running it with verbosity set to diagnostic produces the same output (<code>dotnet run --no-build --verbosity diagnostic</code>), which isn't very helpfull. The same happens when I run the resulting <code>projectname.exe</code> directly.</p>
  
  <p>I'm fairly certain that the program should work but that there is some other underlying error, because the same revision works on the machines of two other people. But I'm really struggeling to figure out what the problem actually is, because it really doesn't seem to be a problem with the autogenerated <code>runtimeconfig.json</code> files.</p>