Don't upgrade unless you need to!
Operating system upgrades are risky. If something goes wrong during the update, your entire server and all of your data on it may be lost.
Ubuntu 14.04 will still receive full support, including patches, security updates, and bug fixes, until 2019.
Do not attempt to upgrade to 16.04 if your server has less than 1GB of memory.
If you have a server with 512MB of memory, you should resize your server to 1GB before upgrading. You can resize back down to 512MB after the upgrade is complete.
Attempting to upgrade a server with less than 1GB of memory may result in database corruption.
Important: Take a server snapshot at your provider before upgrading.
Performing the Upgrade
sudo -i screen -rd.First, SSH in to your server as the root user.
Run the following command to remove the conflicting apache2 packages in case you ever accidentally installed them while customizing your server:
sudo apt-get remove apache2 apache2-bin apache2-data
Run the following command to update your SellCloud APT repository:
sudo replace 14.04 16.04 -- /etc/apt/sources.list.d/sellcloud.list
Now, run this command to start the upgrade:
sudo do-release-upgrade -d
You will be asked the following:
Continue running under SSH? This session appears to be running under ssh. It is not recommended to perform a upgrade over ssh currently because in case of failure it is harder to recover. If you continue, an additional ssh daemon will be started at port '1022'. Do you want to continue? Continue [yN]
Press y and then Enter.
Starting additional sshd To make recovery in case of failure easier, an additional sshd will be started on port '1022'. If anything goes wrong with the running ssh you can still connect to the additional one. If you run a firewall, you may need to temporarily open this port. As this is potentially dangerous it's not done automatically. You can open the port with e.g.: 'iptables -I INPUT -p tcp --dport 1022 -j ACCEPT' To continue please press [ENTER]
Press Enter.
The upgrade preparation will start. You can ignore any Err messages in apt output during the update. These are normal during this stage of the upgrade.
No valid mirror found While scanning your repository information no mirror entry for the upgrade was found. This can happen if you run an internal mirror or if the mirror information is out of date. Do you want to rewrite your 'sources.list' file anyway? If you choose 'Yes' here it will update all 'trusty' to 'xenial' entries. If you select 'No' the upgrade will cancel. Continue [yN]
Press y and then Enter.
Do you want to start the upgrade? 6 installed packages are no longer supported by Canonical. You can still get support from the community. 14 packages are going to be removed. 129 new packages are going to be installed. 449 packages are going to be upgraded. You have to download a total of 344 M. This download will take about 1 minute with your connection. Installing the upgrade can take several hours. Once the download has finished, the process cannot be canceled. Continue [yN] Details [d]
Press y and then Enter.
When prompted with System mail name:, press Enter to keep the default.
When prompted to change the MySQL root password, press Enter to keep the current MySQL root password. You will be asked this same question multiple times during the upgrade. Press Enter each time.
When asked
Restart services during package upgrades without asking?
answer yes.
When asked
What do you want to do about modified configuration file 50unattended-upgrades?
choose the answer keep the local version currently installed.
When asked
Remove obsolete packages? 51 packages are going to be removed. Continue [yN] Details [d]
press y and then Enter.
Finally, you will see the following:
To finish the upgrade, a restart is required. If you select 'y' the system will be restarted. Continue [yN] y
Press y and then Enter.
Your server will now reboot. When your server comes back online from the reboot, the upgrade is complete.
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