The Debian Linux version 7 (codenamed “Wheezy”) support ended on 31st May 2018. It was initial release on May 4, 2013. Each LTS ( initial release on May 4, 2013) support lasts for five years. It means Debian project will not provide any security updates for Debian 7. As Debian Linux 7 Long Term support ends, hence you must upgrade your system to keep it secure. This page list all essentials steps to update your system from Debian 7 to Debian 8.

Debian Linux 7 Long Term Support reached

From the announcement page

The LTS Team will prepare the transition to Debian 8 “Jessie”, which is the current oldstable release. The LTS team will take over support from the Security Team on June 17, 2018.

Debian 8 will also receive Long Term Support for five years after its initial release with support ending on June 30, 2020. The supported architectures include amd64, i386, armel and armhf.

How to upgrade from Debian 7 “Wheezy” to Debian 8 “Jessie”

The following are recommendations for upgrading from Debian 7 “Wheezy” LTS to Debian 8 “Jessie” LTS. First, you must keep backup of all critical data including configuration files, user data, and RDBMS data.

Step 1. Update your /etc/apt/sources.list

Use a text editor such as vim command or nano command:
$ sudo vi /etc/apt/sources.list
Update it as follows:
deb http://deb.debian.org/debian jessie main
deb http://security.debian.org/debian-security jessie/updates main
Save and close the file.

Step 2. Update your system

Type the following apt-get command:
$ sudo apt-get update

Step 3. Install apt from Jessie

Type the following apt-get command:
$ sudo apt-get install apt -t jessie

Step 4. Upgrade your system

Now you can use the apt command:
$ sudo apt upgrade

Step 5. Upgrade your system and remove obsolete packages

Run the following apt command:
$ sudo apt dist-upgrade
You might see prompts and update for configuration files. Apply them as needed. Review all changes carefully.

Step 6. Reboot the Linux box

Run the following command to reboot the Linux server/desktop or laptop:
$ sudo reboot
OR
$ sudo shutdown -r 0

Step 7. Verify it

Type the following command to see your Linux kernel version:
$ uname -mrs
$ uname -a
See your Debian Linux distribution version and other info using cat command:
$ cat /etc/debian_version
Sample outputs:

8.10

Check all your log files on Linux box for any errors using either tail command or grep command:
$ tail -f /var/log/dmesg
$ egrep 'warn|error|critical' /path/to/log/file
Make sure all services are running and required ports are open too:
$ sudo netstat -tulpn
$ sudo ss -tulpn
$ ping cyberciti.biz
$ host cyberciti.biz
$ ps aux | more
$ ps aux | grep apache

Conclusion

The Debian Long Term Support (LTS) Team announced that Debian 7 “Wheezy” support had reached its end-of-life on May 31, 2018. You just learned how to upgrade your version to next Debian 8 LTS version. I strongly suggest that you visit this page for more info and this page for upgrading existing Debian 8 to Debian 9.