ubuntu - 安装 ROS2 "E: Unable to locate package ros-foxy-desktop"出现问题

Question

我尝试在 ubuntu 焦点 fosa (20.04) 上安装 ROS 2。
I went along with this instruction ， 但
执行此命令后:

sudo apt update

我遇到了这个问题:

Hit:1 http://ru.archive.ubuntu.com/ubuntu focal InRelease
Hit:2 http://ru.archive.ubuntu.com/ubuntu focal-updates InRelease                                                                                       
Hit:3 http://ru.archive.ubuntu.com/ubuntu focal-backports InRelease                                                                                                   
Hit:4 http://download.opensuse.org/repositories/home:/Alexx2000/xUbuntu_20.04  InRelease                                                                              
Hit:5 http://security.ubuntu.com/ubuntu focal-security InRelease                                                                                                      
Hit:6 http://packages.osrfoundation.org/gazebo/ubuntu-stable focal InRelease                                       
Get:7 http://packages.ros.org/ros2/ubuntu focal InRelease [4,670 B]
Err:7 http://packages.ros.org/ros2/ubuntu focal InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F42ED6FBAB17C654
Reading package lists... Done
W: GPG error: http://packages.ros.org/ros2/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F42ED6FBAB17C654
E: The repository 'http://packages.ros.org/ros2/ubuntu focal InRelease' is not signed.
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.

之后: sudo apt install ros-foxy-desktop我知道了:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package ros-foxy-desktop

Answer 1

我修好了它。基本上，我添加了新的存储库 key 并删除了旧的。这对我有用:
https://answers.ros.org/question/379190/apt-update-signatures-were-invalid-f42ed6fbab17c654/