While working on exercise 5.1, I am taking the error below. I checked the solution and I did what it said but the errors isn’t solved

user:~/catkin_ws/src/unit_5_services$ roslaunch unit_5_services my_robot_arm.launch
RLException: [my_robot_arm.launch] is neither a launch file in package [unit_5_services] nor is [unit_5_services] a launch file name
The traceback for the exception was written to the log file

I’m having the same issue, while running a robot simulation. it seems to be a problem with source devel/bashrc. it doesn’t recolonize the path, I’m not very sure .

This means that ROS is not finding your package. Make sure it is written like that, and that you have compiled and sourced your workspace in order for ROS to find it:

cd ~/catkin_ws
rm -rf build/ devel/
source devel/setup.bash