ROS installation Ubuntu compatible version

http://wiki.ros.org/ROS/Installation

• Note that older versions of ROS have the same name as Groovy.

Try installing ROS Noetic on Ubuntu 20.10.

20.10 Groovy Gorilla

E: The repository 'http://packages.ros.org/ros/ubuntu groovy Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Error when trying to install normally.

http://packages.ros.org/ros/ubuntu/dists/focal/ Looking here, there is only Focal. In the following, groovy is rewritten to focal.

$ sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu focal main" > /etc/apt/sources.list.d/ros-latest.list'

You can now do apt update,

$ sudo apt install ros-noetic-desktop-full
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 gazebo11 : Depends: libboost-regex1.71.0-icu66 but it is not installable
            Depends: libignition-msgs5 (>= 5.3.0) but it is not going to be installed
            Depends: libignition-transport8 (>= 8.0.0) but it is not going to be installed
            Depends: libprotobuf17 but it is not installable
 gazebo11-common : Depends: ttf-dejavu-core but it is not installable
 gazebo11-plugin-base : Depends: libignition-msgs5 (>= 5.3.0) but it is not going to be installed
                        Depends: libignition-transport8 (>= 8.0.0) but it is not going to be installed
                        Depends: libprotobuf17 but it is not installable
 libgazebo11 : Depends: libboost-regex1.71.0-icu66 but it is not installable
               Depends: libgdal26 (>= 3.0.0) but it is not installable
               Depends: libignition-fuel-tools4 (>= 4.1.0) but it is not going to be installed
               Depends: libignition-msgs5 (>= 5.3.0) but it is not going to be installed
               Depends: libignition-transport8 (>= 8.0.0) but it is not going to be installed
               Depends: libprotobuf17 but it is not installable
               Depends: libtinyxml2-6a (>= 6.0.0) but it is not installable
 libignition-common3-av-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-common3-core-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-common3-events-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-common3-graphics-dev : Depends: libignition-cmake2-dev but it is not installable
                                    Depends: libignition-common3-graphics (= 3.6.0-1~focal) but it is not going to be installed
 libignition-common3-profiler-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-fuel-tools4-dev : Depends: libignition-cmake2-dev but it is not installable
                               Depends: libignition-fuel-tools4 (= 4.2.1-2~focal) but it is not going to be installed
 libignition-math6-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-msgs5-dev : Depends: libignition-cmake2-dev but it is not installable
                         Depends: libignition-msgs5 (= 5.3.0-1~focal) but it is not going to be installed
 libignition-transport8-core-dev : Depends: libignition-transport8 (= 8.1.0-1~focal) but it is not going to be installed
                                   Depends: libignition-cmake2-dev but it is not installable
 libignition-transport8-log-dev : Depends: libignition-cmake2-dev but it is not installable
                                  Depends: libignition-transport8-log (= 8.1.0-1~focal) but it is not going to be installed
 ros-noetic-class-loader : Depends: libpocofoundation62 (>= 1.9.2) but it is not installable
 ros-noetic-controller-manager : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-cv-bridge : Depends: libboost-regex1.71.0-icu66 but it is not installable
 ros-noetic-diagnostic-aggregator : Depends: libboost-regex1.71.0-icu66 but it is not installable
                                    Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-gazebo-plugins : Depends: libprotobuf17 but it is not installable
 ros-noetic-gazebo-ros : Depends: libprotobuf17 but it is not installable
 ros-noetic-gazebo-ros-control : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
                                 Depends: ros-noetic-transmission-interface but it is not going to be installed
 ros-noetic-image-transport : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-kdl-parser : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-laser-assembler : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-laser-filters : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-nodelet : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-pcl-ros : Depends: libpcl-common1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-features1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-filters1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-io1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-search1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-segmentation1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-surface1.10 (>= 1.10.0+dfsg) but it is not installable
 ros-noetic-pluginlib-tutorials : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-rosbag : Depends: libboost-regex1.71.0-icu66 but it is not installable
                     Depends: ros-noetic-rosbag-storage but it is not going to be installed
 ros-noetic-rosconsole : Depends: libboost-regex1.71.0-icu66 but it is not installable
 ros-noetic-rospack : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-rqt-gui-cpp : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
                          Depends: ros-noetic-qt-gui-cpp (>= 0.3.0) but it is not going to be installed
 ros-noetic-rviz : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-urdf : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
E: Unable to correct problems, you have held broken packages.

I got an error and it seems to be difficult. ..