Try disabling the schema consistency. This is one time thing that needs to happen when you upgrade asp.net identity from version 1.0 to 2.0.
public ApplicationDbContext() : base("MyConnection", throwIfV1Schema:false)
Notice I added throwIfV1Schema:false
as a second parameter. Compile it, try to log in so the DB gets updated, do the migrations if needed and then you can remove it.