Upgrade Debian 8 Jessie to Debian 9 Stretch

This guide explains how to upgrade your Debian Linux system from Debian 8 (Jessie) to Debian 9 (Stretch) which was released on 2017-06-17.

These steps can be preformed as an in place upgrade on a live system from either a local terminal or remote SSH session.

Step 1

Prior to upgrading, make sure the current system is up-to-date.

apt-get update && apt-get upgrade

Step 2

Begin the upgrade by switching Debian repositories from Jessie to Stretch. This is accomplished in one of two ways; using the sed command to search and replace all instances automatically, or by editing the source file manually. Choose whichever option you prefer.

Search & Replace with sed.

sed -i 's/jessie/stretch/g' /etc/apt/sources.list

Or edit your source list manually.

vi /etc/apt/sources.list

Replace all instances of "jessie" with "stretch" , for example.

deb http://ftp.us.debian.org/debian/ jessie main non-free contrib
deb-src http://ftp.us.debian.org/debian/ jessie main non-free contrib

deb http://security.debian.org/ jessie/updates main contrib non-free
deb-src http://security.debian.org/ jessie/updates main contrib non-free

deb http://ftp.us.debian.org/debian/ jessie-updates main contrib non-free
deb-src http://ftp.us.debian.org/debian/ jessie-updates main contrib non-free

Becomes.

deb http://ftp.us.debian.org/debian/ stretch main non-free contrib
deb-src http://ftp.us.debian.org/debian/ stretch main non-free contrib

deb http://security.debian.org/ stretch/updates main contrib non-free
deb-src http://security.debian.org/ stretch/updates main contrib non-free

deb http://ftp.us.debian.org/debian/ stretch-updates main contrib non-free
deb-src http://ftp.us.debian.org/debian/ stretch-updates main contrib non-free

Note: Debian is distributed (mirrored) on hundreds of servers worldwide. In our source.list example above we've used a repository within the United States, to speed up downloads you may choose another Debian mirror based on geographic location.

Step 3

Update the package index.

apt-get update

Step 4

Upgrade the minimal base system.

apt-get upgrade

Step 5

Upgrade all other packages and dependencies.

apt-get dist-upgrade

Step 6

Reboot the system.

reboot

Step 7

Verify your release is now Debian 9.

lsb_release -a

Output will be similar to this.

No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 9.0 (stretch)
Release: 9.0
Codename: stretch

Step 8

Verify Kernel version.

uname -mrs

Output will be similar to this.

Linux 4.9.0-3-amd64 x86_64

Step 9

Optionally, free up some disk space by clearing the local repository of retrieved package files.

apt-get clean

apt-get autoremove