Solved
jsensharmaAnswer
Platinum ⭐️⭐️
August 21, 2019
While adding a new Node to ambari cluster it checks various things like existing HDP users / if any HDP related process is already running on the host....
So please check those hosts listed in the WARNING message and then SSH to those hosts if needed stop OR kill those Processes (if those are not needed currently). Else ignore the warning and then retry from Ambari UI. But better to stop those WARNING listed processes for now.

