The Nationals had a trade in place to send Bryce Harper to the Astros at the trade deadline. According to Ken Rosenthal, Nationals ownership, led by Ted Lerner, stopped the deal from being finalized.
Apparently the Nationals preferred to not get anything in return for Harper, because that's exactly what is going to happen. He's a free agent and will be signing with a new team.
The fact that the Nationals could have turned Bryce Harper's free agency into a prospect or two and chose not to, tells you all you need to know about how poorly this organization has been run over the years.