The error says that "user_objects" does not exist.
To access the database (in ubuntu-server installed using install-ns scripts) for checking queries manually and find out more about the tables:
~$ sudo su - postgres
~$ psql 5-9
psql (9.3.16)
Type "help" for help.
5-9=# \d user_objects
Did not find any relation named "user_objects".
5-9=#