On a system you have modified heavily, you may wish to enter d and inspect the list of packages to be removed, in case it includes anything you'll need to reinstall later.
You may need to press a key here to exit to your local prompt, since your SSH session will have terminated on the server end.
On Digital Ocean systems, it is safe to ignore this warning and proceed with the upgrade, since a local mirror for 16.04 is in fact available. Continue [y N] Details [d] New packages will now be retrieved, then unpacked and installed.
Enter y: Updating repository information No valid mirror found While scanning your repository information no mirror entry for the upgrade was found. Even if your system is on a fast connection, this will take a while.
has not informed us of this, you can use the console available from the Digital Ocean Control Panel to connect to your Droplet without running SSH.