Face Null Value Error.

Hello every one .I have face a null value error

I have use three table use with navigation

1. UserMatser -ParentTable

2.UserSub -Child Table

it's my query

var Result = _context.UserSubscriptionMaster.Where(x => x.User.UserId == Id).

Select(x => new UserViewProfile()

{

UserName = x.User.UserName,

UserProfilePic = x.User.UserProfilePic,

Plans = x.Plan.PlanName,

UserEmail = x.User.UserEmail

}).FirstOrDefault();

if (Result != null)

obj_Detail.ViewUserDetail = Result;

It's working .But it's working with data in two table with same id. I have face null value in Data not availabe in two table .