My Solutions:

• Remove configuration in .csproj file. Remove: <OutputType>Exe</OutputType>

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• Add Main() endpoint

There are 2 mainly reasons for this error:

1. Configurations .csproj file the .NET project will be built into .exe / .dll file ( by run 'dotnet build'). Incase, we config the .csproj with option: Exe the .NET project will be built to .exe file that need an Main() endpoint. So that why the error happening.

2. Don't have Main() endpoint