vs net core Project Exception Resolution-project.assets.json’ not found. Run a NuGet package restore to generate this file

Error occurred while restoring NuGet packages: The local source ‘C:\Users\think\Downloads’ doesn’t exist.

1>—— Build started: Project: TensorFlow.Binding, Configuration: Debug Any CPU ——

2>—— Build started: Project: Benchmark, Configuration: Debug Any CPU ——

2>C:\Program Files\dotnet\sdk\2.2.207\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(208,5): error NETSDK1004: Assets file ‘D:\TensorFlow.NET20191228\TensorFlow.NET\src\TensorFlowNet.Benchmarks\obj\project.assets.json’ not found. Run a NuGet package restore to generate this file.

solution steps as follows:

PM> dotnet restore

C:\Program Files\dotnet\sdk\3.1.100\NuGet.targets(123,5): error : local resource”C:\Users\think\Downloads” not exist [D:\TensorFlow.NET20191228\TensorFlow.NET\TensorFlow.NET.sln]

PM>main menu/build/build solution

========== Build: 3 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========