最近有用户不断反馈3cx自动更新时会失败，尝试过多次都是一样的。
从更新日志里提取的结果如下：
Ign:1 http://cdn-aws.deb.debian.org/debian stretch InRelease
Hit:2 http://cdn-aws.deb.debian.org/debian stretch-updates InRelease
Hit:3 http://security.debian.org/debian-security stretch/updates InRelease
Hit:4 http://downloads-global.3cx.com/downloads/debian stretch-testing InRelease
Ign:5 http://repo.saltstack.com/apt/debian/9/amd64/archive/2019.2.0 stretch InRelease
Hit:6 http://downloads-global.3cx.com/downloads/debian stretch InRelease
Hit:7 http://cdn-aws.deb.debian.org/debian stretch Release
Err:8 http://repo.saltstack.com/apt/debian/9/amd64/archive/2019.2.0 stretch Release
404 Not Found [IP: 13.32.143.114 80]
Reading package lists...
E: The repository 'http://repo.saltstack.com/apt/debian/9/amd64/archive/2019.2.0 stretch Release' does no longer have a Release file.出现这种情况一般是没有使用3CX官方的ISO镜像安装3CX，而且第三方存储库过时了。
解决方法如下：
以root用户身份登录你的Debian后台，然后输入如下命令，就能解决
wget -O - https://downloads.3cx.com/downloads/misc/debianpatches/9/16/0/5/20200619-os-update.sh | bash此命令行运行成功后，3CX就能正常更新了。