ROS_DISTRO was set to 'melodic' before

As an absolute beginner of ROS2, when I followed the instructions in the ROS2 BASIC IN 5 DAYS on the ROSDS platform, it said that “ROS_DISTRO was set to ‘melodic’ before. Please make sure that the environment does not mix paths from different distributions”. I cannot figure out the specific reason. After searching the same problem, I still could not solve it. I would like to ask seniors for help.
Thanks for your attention.


Hello @sunsmile0708,

Don’t worry, that’s not an error. It’s just letting you know that you have switched from a ROS Melodic environment to a ROS2 Crystal environment, so be careful to not mix things from both distributions.


Thanks for your prompt reply. I do appreciate it!