I am following the instructions at Ubuntu Development Environment | PX4 User Guide to install the PX4 Development Environment on Ubuntu 20.04.3. I get the following errors when executing the ubuntu_sim_ros_melodic.sh script (clicked on link which brought me to https://raw.githubusercontent.com/PX4/Devguide/master/build_scripts/ubuntu_sim_ros_melodic.sh):
Reading package lists… Done
Building dependency tree
Reading state information… Done
Note, selecting ‘libpython2.7-stdlib’ instead of ‘python-argparse’
Note, selecting ‘python-dev-is-python2’ instead of ‘python-dev’
Package python-empy is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
Package python-pip is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
python3-pip
E: Package ‘python-empy’ has no installation candidate
E: Unable to locate package python-toml
E: Package ‘python-pip’ has no installation candidate