How To Upgrade Ubuntu 14.10 to 15.04 Vivid Vervet

Ubuntu 15.04 is the version of the Ubuntu operating system released in April, 2015. The development codename given to this release is "Vivid Vervet".

Before You Start

• You can directly upgrade to Ubuntu 15.04 ("Vivid Vervet") from Ubuntu 14.10 ("Utopic Unicorn").
• Be sure that you have all updates applied to your current version of Ubuntu before you upgrade.
• Before upgrading it is recommended that you read the release notes for Ubuntu 15.04, which document caveats and workarounds for known issues in this version.

If you have a version of Ubuntu other than 14.10, please see UpgradeNotes for information on how to upgrade.

Upgrade from 14.10 to 15.04

Ubuntu Desktops 14.10 to 15.04 (Recommended)

You can easily upgrade over the network with the following procedure.

1. Run the update-manager application from the Unity Dash or a command line
2. In Update Manager, click the Settings... button, and enter your password to start the Software Sources application.
3. Select the sub menu Updates from the Software Sources application.
4. Confirm the "Notify me of a new Ubuntu version:" option is set to "For any new version", and change it if otherwise.
5. Close the Software Sources application and return to Update Manager.
6. In Update Manager, click the Check button to check for new updates.
7. If there are any updates to install, use the Install Updates button to install them, and press Check again after that is complete.
8. A message will appear informing you of the availability of the new release.
9. Click Upgrade.
10. Follow the on-screen instructions.

Kubuntu Desktops (Recommended)

Direct upgrades to Kubuntu 15.04 are supported from Kubuntu 14.10.

• Upgrade Kubuntu 14.10 to 15.04

Ubuntu Servers (Recommended)

1. If you installed from 14.04 or 12.04 originally you will need to remove LTS upgrade restrictions. Replace Prompt=lts with Prompt=normal: 

   sudo pico /etc/update-manager/release-upgrades

2. Install update-manager-core if it is not already installed:

   sudo apt-get install update-manager-core

3. Launch the upgrade tool:

   do-release-upgrade

4. Follow the on-screen instructions.

Source Link : https://help.ubuntu.com/community/VividUpgrades