Your startup project doesn't reference Microsoft.EntityFrameworkCore.Design

Question

I have 2 projects in my solution, I have a project with Entity Framework Core installed:

And in the other ASP.NET Web API project I have these packages:

<?xml version="1.0" encoding="utf-8"?> <packages>   <package id="Antlr" version="3.5.0.2" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights" version="2.5.1" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights.Agent.Intercept" version="2.4.0" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights.DependencyCollector" version="2.5.1" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights.PerfCounterCollector" version="2.5.1" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights.Web" version="2.5.1" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights.WindowsServer" version="2.5.1" targetFramework="net461" />   <package id="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel" version="2.5.1" targetFramework="net461" />   <package id="Microsoft.AspNet.Mvc" version="5.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.Razor" version="3.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.TelemetryCorrelation" version="1.0.0" targetFramework="net461" />   <package id="Microsoft.AspNet.Web.Optimization" version="1.1.3" targetFramework="net461" />   <package id="Microsoft.AspNet.WebApi" version="5.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.WebApi.Client" version="5.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.WebApi.Core" version="5.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.WebApi.HelpPage" version="5.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.WebApi.WebHost" version="5.2.4" targetFramework="net461" />   <package id="Microsoft.AspNet.WebPages" version="3.2.4" targetFramework="net461" />   <package id="Microsoft.CodeDom.Providers.DotNetCompilerPlatform" version="2.0.0" targetFramework="net461" />   <package id="Microsoft.Web.Infrastructure" version="1.0.0.0" targetFramework="net461" />   <package id="Newtonsoft.Json" version="11.0.1" targetFramework="net461" />   <package id="System.Diagnostics.DiagnosticSource" version="4.4.1" targetFramework="net461" />   <package id="WebGrease" version="1.6.0" targetFramework="net461" /> </packages> 

When I run Add-Migration in PMC:

Your startup project 'API' doesn't reference Microsoft.EntityFrameworkCore.Design. This package is required for the Entity Framework Core Tools to work. Ensure your startup project is correct, install the package, and try again.

I installed Microsoft.EntityFrameworkCore.Design in the startup project instead of the data project that will contain all the entities and now it works, is this how the project should be setup?

Answer 1

I found the solution here.

In short, edit your csproj file, and add to your PropertyGroup section following entry:

<GenerateRuntimeConfigurationFiles>True</GenerateRuntimeConfigurationFiles> 

Answer 2

None of the options worked for me. But the one I tried on this topic worked: EF Core 3 design time migrations broken by Microsoft.EntityFrameworkCore.Design DevelopmentDependency

I just commented out the following after importing the package to the Data project:

<ItemGroup> <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="3.1.4" /> <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.1.5">   <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>   <!--<PrivateAssets>all</PrivateAssets>--> </PackageReference> 

Thank you so much Microsoft by breaking the existing projects every time when you release a new .NetCore update!