Upgrading a distribution to a newest version is not a task that must be considered safe. i-MSCP install/modify numerous files on your system and when you need to process distribution upgrade, you must really think before acting.

Here are given the tasks that must be done prior any upgrade attempt:

1. Do a backup of all you data (/var/wwww/virtual, /var/mail/virtual, /etc/imscp …)
2. Do a dump of all your databases
3. Cleanup your /etc/apt/sources.list file (you must remove any unofficial repository, including those which are added by the i-MSCP installer)
4. Update your /etc/apt/sources.list according the distribution to which you want migrate
5. Remove the /etc/apt/preferences.d/imscp file if any
6. Stop imscp_daemon and imscp_panel services

Once all these tasks done, you should be able to upgrade safetly with the following commands:

  # aptitude update
  # aptitude dist-upgrade