I followed the instructions and installed ROS Melodic on an Ubuntu 18.04 instance on Amazon EC2. Then I tried to install the necessary packages for gazebo, e.g.,

sudo apt-get install ros-melodic-turtlebot3-gazebo ros-melodic-turtlebot3-applications ros-melodic-turtlebot3-autorace ros-melodic-turtlebot3-example ros-melodic-turtlebot3-msgs ros-melodic-turtlebot3-simulations

Then I tried to check the installation by running:

roslaunch turtlebot3-gazebo turtlebot3-world.launch

and got

Segmentation fault (core dump)
[gazebo-gui-2] process has died [pid 479, exit code 139, cmd /opt/ros/melodic/lib/gazebo_ros/gzclient _name:=gazebo_gui _log:=/home/ubuntu/.ros/log/d3e9ec9e-073c.../gazebo_gui-2.log]

Does anyone know what might be wrong? Thanks in advance