You can upgrade from minor or major release of Ubuntu easily and recommended for all users.
Make a backup – it cannot be stressed enough how important it is to make a backup of your system before you do this.
Most of the actions listed in this post are written with the assumption that they will be executed by the root user running the bash or any other modern shell.
This is the recommended command as the server has no graphic environment or if the server is to be upgraded over a remote connection using ssh client: Update Manager should open up and tell you: New distribution release ‘14.04 LTS’ is available.
Just click Upgrade and follow the on-screen instructions to upgrade your desktop systems.
Please note that all LTS desktop users need to wait till the first release called Ubuntu LTS v14.04.1 will be released by Canonical LTD.
successfully complete, upgrades between LTS releases are not enabled by default until the first point release, and it is recommended to wait until the 16.04.1 point release to upgrade.
On Digital Ocean systems, an upgraded Ubuntu 14.04 system will be left with an older kernel which may not be upgradeable for some time.
The Ubuntu operating system's next Long Term Support release, version 16.04 (Xenial Xerus), is due to be released on April 21, 2016.Although it hasn't yet been released at the time of this writing, it's already possible to upgrade a 15.10 system to the development version of 16.04.This may be useful for testing both the upgrade process and the features of 16.04 itself in advance of the official release date.This guide will explain the process for systems including (but not limited to) Digital Ocean Droplets running Ubuntu 15.10.Warning: As with almost any upgrade between major releases of an operating system, this process carries an inherent risk of failure, data loss, or broken software configuration.Comprehensive backups and extensive testing are strongly advised. Although many systems can be upgraded in place without incident, it is often safer and more predictable to migrate to a major new release by installing the distribution from scratch, configuring services with careful testing along the way, and migrating application or user data as a separate step.