This usually occurs during database migration.

The above error indicates that the class library or project you specified cannot be found. You can use — project to specifically declare the project path (where to find the csproj file)

example:

dotnet ef migrations add AddTable_Products  --project src\Adu.Store.EntityFrameworkCore

The following meaning shows that the path of csproj file is in SRC\adu.store.entityframeworkcore folder