This article is a step by step tutorial on how to upgrade your Ubuntu 12.04 LTS Precise Pangolin to Ubuntu 14.04 Trusty Tahr. This upgrade is been carried out on a VirtualBox, I cannot guaranty if this would work in your case or not. Care needs to be taken if upgrading a LIVE system.
Step 1: Backup your Data
– I am afraid you would have to backup your files and documents. Its safer to do this as you may not predict or anticipate what might happen during the upgrade or if the OS might become unstable.
Step 2: Install Updates
– To avoid any possible system crash during upgrade, its always best practice to update your current system to latest updates. From terminal run the following command
sudo apt-get update sudo apt-get dist-upgrade
– To confirm that there are no updates pending, open Software Update Manager and ensure status shows ‘System Up-To-Date’
Step 3: Upgrade System
sudo do-release-upgrade -d
– The following message might appear, type Y to continue
Note: This stage will take a while depending on your internet connection speed
– After upgrade is completed, type Y to restart the system
– After reboot, we have now successfully upgraded Ubuntu 12.04 LTS to 14.04 LTS
Step 4: Install Guest Additions Tool
sudo apt-get install virtualbox-*
Please post your errors here if you encounter any issues