Upgrade to 18.04 from 17.10
-d is for development releases. Do not put that command-line [option] in the command.
If you want a fresh and stable 18.04 simply type:
sudo do-release-upgrade
Now press enter
You need to wait for some days (more like a week or two) before the Update Manager tells you.
If you don't want to wait so long you can use the following command:
sudo do-release-upgrade -d
Make sure nothing is going to interupt this process.