# Revision history [back]

You .bashrc probably contains set -u.

The proper fix would be to change the line in /opt/ros/electric/setup.sh:

export PYTHONPATH=${ROS_ROOT}/core/roslib/src:${PYTHONPATH}


to

export PYTHONPATH=${ROS_ROOT}/core/roslib/src:${PYTHONPATH-}


I would say that this is the intended behaviour.