Trying ASP.NET Identity

I've created a project, File/New/Project... - ASP.NET Web Application and thenWeb Forms (have also tried MCV with same result) with Authentication set toIndividual User Accounts.

When I run it for the first time I click on Register and enters valid values in Email, Password and Confirm password, just as all the tutorials I've seen. Then I click in Register and after a (rather long) while the site crashes in Register.aspx and on line

IdentityResult result = manager.Create(user, Password.Text);

saying "An exception if type 'System.Data.SqlClient.SqlException' occured in mscorlib.dll but was not handled in user code"

Now it doesn't follow the channel 9 tutorials anymore;) What's wrong? I'm running Windows 10, Visual Studio Community 2015 and SQL Server 2014 (Express or whatever it's called).