Conguratulations on the releasing .NET Core 3.0 and ASP.NET Core 3.0! Today's theme is about upgrading ASP.NET Core from ver.2.2 to ver.3.0. What I did Creating an empty ASP.NET Core project(ver.2.2.402) Adding EntityFrameworkCore by NuGet Adding some codes Upgrading to ver.3.0.100 Fixing some problems Setup Environments .NET Core : ver.2.2.402, ver.3.0.100 Microsoft.EntityFrameworkCore : ver.2.2.6, ver.3.0.0 Npgsql.EntityFrameworkCore.PostgreSQL : ver.2.2.4, ver.3.0.1 Windows10 : ver.1903 Rider : ver.2019.2.3 PostgreSQL : ver.12.0 Creating the base project UpgradeSample.csproj <Project Sdk="Microsoft.NET.Sdk.Web"> <PropertyGroup> <TargetFramework>netcoreapp2.2</TargetFramework> <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel> </PropertyGroup> <ItemGroup> <PackageReference Include="Microsoft.AspNetCore.App" /> <PackageReference Include=...