for everyone experiencing the error in the screenshot... check if there is some hidden central user management system active - which deletes your users...
are you referring to the "hdfs client"? if so, yes.
The Master also contains both, ambari-server as well as the ambari-agent.
Your files are owned by UID's instead of usernames.. May be your unix team has changed the UID's of service users..
Change the ownership of files owned by 37990 to 'hdfs' user by using chown linux command..