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The reason why rosversion roslaunch experiences this occur is most likely due to not being sourced correctly. If it isn't sourced correctly, it wouldn't be able to locate ROS, thus not being able to find and output the version of your ros.
Double check that you source your bash correctly with source ~/opt/ros/kinetic/setup.bash. If the error still occurs, make sure you have sourced your workspace with source ~/ros_catkin_ws/install_isolated/setup.bash.