dotnet build - The local source '...' doesn't exist

실습 중에 이런 오류가 발생한다면?

c:\temp\consoleapp>dotnet new console

c:\temp\consoleapp>dotnet run
Hello World!

c:\temp\consoleapp>dotnet build --runtime win-x64
Microsoft (R) Build Engine version 16.7.0+7fb82e5b2 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
C:\Program Files\dotnet\sdk\3.1.402\NuGet.targets(128,5): error : The local source 'C:\MyNuGet' doesn't exist. [c:\temp\consoleapp\consoleapp.csproj]

Build FAILED.

C:\Program Files\dotnet\sdk\3.1.402\NuGet.targets(128,5): error : The local source 'C:\MyNuGet' doesn't exist. [c:\temp\consoleapp\consoleapp.csproj]
    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:00.84

C:\temp> dotnet nuget list source
Registered Sources:
  1.  nuget.org [Enabled]
      https://api.nuget.org/v3/index.json
  2.  Microsoft Visual Studio Offline Packages [Enabled]
      C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\
  3. My [Enabled]
      C:\MyNuGet

c:\temp\consoleapp> dotnet new nuget
The template "NuGet Config" was created successfully.

c:\temp\consoleapp>dotnet build --runtime win-x64
Microsoft (R) Build Engine version 16.7.0+7fb82e5b2 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  Restored c:\temp\consoleapp\consoleapp.csproj (in 7.39 sec).
  consoleapp -> c:\temp\consoleapp\bin\Debug\netcoreapp3.1\win-x64\consoleapp.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:11.57

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageSources>
    <!--To inherit the global NuGet package sources remove the <clear/> line below -->
    <clear />
    <add key="nuget" value="https://api.nuget.org/v3/index.json" />
  </packageSources>
</configuration>