器：source dir of debian

the source dir of debian:

if something like:

Hit:13 http://mirrors.aliyun.com/debian stretch Release
Err:15 http://mozilla.debian.net jessie-backports Release               
  404  Not Found
Err:16 http://ppa.launchpad.net/fcitx-team/nightly/ubuntu eoan Release
  404  Not Found
Reading package lists... Done
E: The repository 'http://mozilla.debian.net jessie-backports Release' does not have a Release file.
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.
E: The repository 'http://ppa.launchpad.net/fcitx-team/nightly/ubuntu eoan Release' does not have a Release file.
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.

 

then go to 

/etc/apt/sources.list.d

 

and rm sth,

sudo rm debian-mozilla.list fcitx-team-ubuntu-nightly-eoan.list 

sudo apt update