RLException: error loading <rosparam> tag:file does not exist [3]

Currently, I am following the instruction of the Unit 3 “Motion Planning using graphical Interfaces |” until the exercise 2.2 after the movit package was created it’s asked to run the following command to use rviz demo:
roslaunch rbkairos_moveit_config demo.launch
but I get the following error

What is the wrong with file 3 ??

Hello @mwk0900.na ,

It looks like you are trying to load this file named 3 which doesn’t exist. What is the file where you have this line?

Actually I deleted moveit package and remade it again and the error disappeared, thanks !