سلام وقتتون بخیر. من وقتی دستور sudo apt-get update رو وارد میکنم به این ارور بر میخورم
 404 Not Found [IP: 91.189.88.142 80]
 404 Not Found [IP: 195.135.221.134 80]
 404 Not Found [IP: 91.189.91.39 80]
 404 Not Found [IP: 91.189.91.38 80]
Reading package lists... Done
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.
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.
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.
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.