Today I was trying to make an initial migration using Entity framework. I encountered an error when calling dotnet ef migrations add InitialCreate:
C:\Users\peter\source\repos\WebApplication\MyDbContext> dotnet ef migrations add InitialCreate
Build started...
Build succeeded.
Unable to create an object of type 'MyDbContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
The issue was that I had not declared a parameterless constructor:
public MyDbContext() { }
If you were trying to do a migration you could use the following in the empty constructor (UseSqlServer for MSSQL server):
optionsBuilder.UseSqlServer("ThisIsJustForMigrations");
When calling UseSqlServer you have provided a non-empty and not null string, but it does not have to be a connection string to a database that is reachable. It can use the previous snapshot to make the migration.
I hope this helps, feel free to leave a comment down below!