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So I finished an installation of noetic before I realized that the most updated version of the LIDAR driver I was looking to use was only compatible with kinetic or melodic.

So I uninstalled noetic with the following commands:

sudo apt remove ros-noetic-*

sudo apt autoremove

then I removed the noetic entry from my bash, and deleted the

ros-latest.list file

from the



But now when I try to follow the steps to install melodic, I get a

E: ros-melodic-desktop-full not found error

The only thing different when I follow the steps for noetic would be the fact that I get a 'number of keys unchanged' message, but I'm not sure if that matters since noetic and melodic seem to use the same command for that.

I'm at a loss right now, and I'd appreciate it if anyone can point me in the right direction. Thanks!

Originally posted by hmrbcnt on ROS Answers with karma: 3 on 2021-02-19

Post score: 0


1 Answer 1


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Melodic is not supported on Ubuntu Focal (20.04), so that would explain why apt can't find it.

You'll have to downgrade to Ubuntu Bionic (18.04) to install ROS Melodic.

Or use something like Docker to run a ros:melodic image (note that while this is certainly doable, if you're just starting out, this may be a bridge-too-far).

Or you could build the lidar driver you mention (would that be the velodyne package? From your #q370291) from source in a Catkin workspace -- there is a good chance that will "just work" (but no guarantees).

Edit: for more details (links to the relevant REP 3 Target Platforms fi) see #q351321, #q353554, #q371501, #q350668, or #q366244.

Originally posted by gvdhoorn with karma: 86574 on 2021-02-19

This answer was ACCEPTED on the original site

Post score: 2

Original comments

Comment by hmrbcnt on 2021-03-07:
Thank you, unfortunately it never occurred to me that it was an Ubuntu version problem. I've installed a new installation. Thanks!


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