This post shows you how to fix 'Assets file '..\obj\project.assets.json' not found. Run a NuGet package restore to generate this file.
C:\Program Files\dotnet\sdk\3.1.302\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets
To solve the problem you can select Tools=>Nuget Package Manager=>Package Manager Console
then enter dotnet restore.
