“Klasa startup.cs brakuje w .NET 6” Kod odpowiedzi

Klasa startup.cs brakuje w .NET 6

In .NET 6 Microsoft has removed the Startup.cs class. 
Now when you'll add a connection string then you've to use builder.Services.
AddDbContext The old way is services.AddDbContext

Just use builder.Services and then you can achieve what you want.