HOWTO : Upgrade Ubuntu Server 16.04 to 18.04

Ubuntu 18.04 LTS is just released. It is a high time to upgrade your Ubuntu Server 16.04 LTS to 18.04 LTS. To upgrade it, make sure you have sufficient free space.

Step 1 :

sudo apt install update-manager-core
sudo do-release-upgrade -d

You need to answer "Y" to all questions asked.

Step 2 :

Make sure to enable all the required repositories at /etc/apt/source.list.d/ and then run the following command.

sudo apt update

Step 3 :

If you have application that works only on Java 8, make sure to do the following.

update-java-alternatives -l
sudo update-java-alternatives -s java-1.8.0-openjdk-amd64

or

sudo update-alternatives --config java

Then, select Java 8

Step 4 :

If your system is running PHP, you need to reinstall all the required packages. For example,

sudo apt-get install php7.2-cgi php7.2 php7.2-cli php7.2-mysql php7.2-curl php7.2-gd php7.2-intl php7.2-imap php7.2-pspell php7.2-recode php7.2-sqlite3 php7.2-tidy php7.2-xmlrpc php7.2-xsl apache2-utils php7.2-fpm php-memcache php-imagick mysql-server mysql-client php7.2-mbstring php7.2-zip

Make sure to do the following when you are using php7.2-fpm on Apache2 :

sudo a2enmod php7.2
sudo a2enconf php7.2-fpm
sudo systemctl enable php7.2-fpm
sudo systemctl enable apache2
sudo systemctl restart php7.2-fpm
sudo systemctl restart apache2

That's all! See you.