Profile Base GetProfile command throws null type in CreateInstance

I am working on a web application that uses built-in security classes to create new users
newuser = MembershipUser.Create(relevant parameters)
that is all well and good
it then issues a Profile.GetProfile(newuser.UserName) which drills down to a System.Activator.CreateInstance(Type type, Boolean nonPublic)
which throws a Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.ArgumentNullException: Value cannot be null. Parameter name: type
it works fine in dev (visual Studio 2015 Community) the current site was developed on an older machine, probably Visual Studio 2010 and works just fine
why am I getting these errors - and how do I fix it?