Err:1 http://mirrors.tuna.tsinghua.edu.cn/ros/ubuntu xxxxxx 404 Not Found [IP: 101.6.8.193 80]

使用sudo apt-get install ros-melodic-teb-local-planner
安装软件，报这个错，搜到的解决方法用不了
后面发现是镜像源里面有这个文件，前面的都对，就上传日期的那个后缀不对导致找不到安装的包
经过搜所，发现是DNS解析有问题

解决方法：
首先改DNS https://note.qidong.name/2020/05/resolvconf/
修改 /etc/resolv.conf文件 添加 202.106.0.20
这个是北京联通的 然后执行sudo apt-get update
会有

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://mirrors.tuna.tsinghua.edu.cn/ros/ubuntu bionic Release: The following signatures were invalid: EXPKEYSIG F42ED6FBAB17C654 Open Robotics <info@osrfoundation.org>
W: Failed to fetch http://mirrors.tuna.tsinghua.edu.cn/ros/ubuntu/dists/bionic/Release.gpg  The following signatures were invalid: EXPKEYSIG F42ED6FBAB17C654 Open Robotics <info@osrfoundation.org>
W: Some index files failed to download. They have been ignored, or old ones used instead.

这样的报错
执行 sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F42ED6FBAB17C654
后面的key是报错上的key，复制一下就行

再执行sudo apt-get update
最后 sudo apt-get install ros-melodic-teb-local-planner
成功安装！