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:

Answer 1

There is absolutely NO reason to install Microsoft.EntityFrameworkCore.Design to your API project while having a separate Data project.

Quick solution

When using add-migration, just add a parameter to set the -StartUpProject to your Data proj (by default I presume your startup project is the API proj).

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Example add-migration command below:

add-migration {migration_name} -StartUpProject {your_data_proj_name} -project {your_data_proj_name} -v

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Example update-database command below:

add-migration {migration_name} -StartUpProject {your_data_proj_name} -project {your_data_proj_name} -v

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I hope this help you guys

PS: more info about the add-migration params can be found here