在实体对象中访问导航属性里的属性值出现异常“There is already an open DataReader associated with this Command which must be closed first”

public class User
    {
        public long UserId { get; set; }
        public string UserName { get; set; }
        public string UserPwd { get; set; } 
        public DateTime UserCreateDate { get; set; }
        public DateTime LastLoginDate { get; set; }
        public DateTime LastActivityDate { get; set; }
        public int UserRoleId { get; set; }

        public virtual UserProfile UserProfile { get; set; }
    }

public class UserProfile
    {
        [Key, ForeignKey("User")]
        public long UserId { get; set; }
        public int Gender { get; set; }
        public string NickName { get; set; }
        public string Signature { get; set; }
        public string Intro { get; set; }
        public DateTime? Birth { get; set; }
        public string Location { get; set; }
        public string Website { get; set; }
        public string Qq { get; set; }
        public string WeiBo { get; set; }
        public string Medals { get; set; }
        public string Phone { get; set; }
        public string Email { get; set; }
        public bool IsSendEmail { get; set; }

        public virtual User User { get; set; }
    }