Unable to communicate with master!

Hi! I’m getting this error when I try to run a command(rostopic list) in Shell. Does anyone know what is happening? Thanks in advance

It would help if you provided more information about the error you are receiving a screen shot of the error along with the exact command would be the most helpful.

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Hi @hskramer,
Yes, here the screen shot:
I wanted to know what topics are involved in order to see the evolution of them when I send a goal to the robot, but I’m getting this error.

For ros2 you want to use the ros2 command and for topics it should be ros2 topic list to see all the ros2 command can do just run ros2 -h for the help. In ros2 as you may already know their is no master and the commands that work in ros1 no longer apply in ros2. But you can still get all the information and more with this command its very similar to the commands used in ros1. This is a link to a pdf for ros2


I come from ros1 and I didn’t know commands changed for ros2. Command “ros2 topic list” works perfectly, as I see in the pdf most of them are similar to ros1 but adding a 2 and a space between. I will do ROS2 Basics course first to have a better understanding of how it works.

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