version: foxy

apt install

sudo apt-get install ros-foxy-serial-driver 
[sudo] password for mi: 
Sorry, try again.
[sudo] password for mi: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  ros-foxy-serial-driver
0 upgraded, 1 newly installed, 0 to remove and 769 not upgraded.
Need to get 9,508 B of archives.
After this operation, 61.4 kB of additional disk space will be used.
Err:1 http://packages.ros.org/ros2/ubuntu focal/main amd64 ros-foxy-serial-driver amd64 0.0.6-1focal.20210423.022509
  404  Not Found [IP: 64.50.233.100 80]
E: Failed to fetch http://packages.ros.org/ros2/ubuntu/pool/main/r/ros-foxy-serial-driver/ros-foxy-serial-driver_0.0.6-1focal.20210423.022509_amd64.deb  404  Not Found [IP: 64.50.233.100 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

Apt update error:

W: An error occurred during the signature verification.
 The repository is not updated and the previous index files will be used.
 GPG error: http://packages.ros.org/ros/ubuntu focal InRelease: The following signatures were invalid: EXPKEYSIG F42ED6FBAB17C654 Open Robotics <[email protected]>

Solution:

 curl http://repo.ros2.org/repos.key | sudo apt-key add -