Frequently, I have clients inquiring about a barn door for a location that doesn't have a header. What I mean by "no header" this that the door opening goes all the way to the ceiling and there is no place to attach the track. While this looks like it's a non-starter, it's actually a great way to add some interesting design elements to your home.
There are two ways to fix the problem but both involve adding a support/header for the track to be connected to. After adding the header, most people don't want to go through the cost and hassle of adding drywall over the new support/header to match the existing walls. To avoid this, we actually cover the support with wood that matches the barn door and take it up to the ceiling. Some people (and this is personally my favorite way to do it) extend the wood from above the door along the wall to look like a rustic beam. This is what I was referring to when I was talking about using this challenge as an opportunity to add design elements.
If you have any questions about this or other projects, don't hesitate to reach out.