apt update error with ubuntu 18.10 cosmic version [closed]

Problem: impossible to execute ‘apt-get update’ (Ubuntu 18.10)

Ubuntu 18.10 cosmic end of life

I tried to upgrade my system version but i got the same error of apt-get update command

$ apt update
Ign:1 http://archive.ubuntu.com/ubuntu cosmic InRelease
Ign:2 http://security.ubuntu.com/ubuntu cosmic-security InRelease
Ign:3 http://archive.ubuntu.com/ubuntu cosmic-updates InRelease
Ign:4 http://archive.ubuntu.com/ubuntu cosmic-backports InRelease
Err:5 http://security.ubuntu.com/ubuntu cosmic-security Release
  404  Not Found [IP: 91.189.88.173 80]
Err:6 http://archive.ubuntu.com/ubuntu cosmic Release
  404  Not Found [IP: 91.189.88.31 80]
Err:7 http://archive.ubuntu.com/ubuntu cosmic-updates Release
  404  Not Found [IP: 91.189.88.31 80]
Err:8 http://archive.ubuntu.com/ubuntu cosmic-backports Release
  404  Not Found [IP: 91.189.88.31 80]
Reading package lists... Done
E: The repository 'http://security.ubuntu.com/ubuntu cosmic-security 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://archive.ubuntu.com/ubuntu cosmic 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://archive.ubuntu.com/ubuntu cosmic-updates 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://archive.ubuntu.com/ubuntu cosmic-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.

Source: StackOverflow