Upgrade Ubuntu

This path may not work for everyone but it did for our servers. Here are the steps:

1. apt-get clean && apt-get update && apt-get upgrade

2. apt-get dist-upgrade

3. apt-get clean

4. do-release-upgrade

5. reboot

6. (if you use pureftp) apt-get remove pure-ftpd-common pure-ftpd && apt-get install pure-ftpd-common pure-ftpd

7. for servers using mysql databases:

apt-get install php-mysql

service apache2 restart