CreateUser issue in VS2013 but not in VS2012

In my VS2012 ASP.NET Web Forms app, I had no problem creating a user like this:
MembershipUser user = Membership.CreateUser(tempUser, password, adminEmail); But today I upgraded to VS2013 and am getting this exception message:
The password-answer supplied is invalid.
In my web.config file, I've defined users this way:
    <roleManager enabled="true">      <providers>        <add connectionStringName="Inc_DB" applicationName="/Website"          name="CustomizedRoleProvider" type="System.Web.Security.SqlRoleProvider" />      </providers>    </roleManager>    <membership defaultProvider=& ...