This question already has an answer here:
Edit : Note that it is not yet possible to migrate from 16.04.05 LTS to 18.04.1 LTS. Today is Tuesday, August 7.... The release of 18.04.1 LTS took place on July 26... They must have simply forgotten to enable the "For long-term support versions" option in "Notify me of a new Ubuntu version", in the "Software Updater" options... Someone absolutely must tell them please.
This documentation https://help.ubuntu.com/community/BionicUpgrades indicates, in the part titled "Upgrade from 16.04 or 17.10 to 18.04 > Upgrading Ubuntu Desktops to 18.04 (Recommended)" that in order to migrate from 16.04 (16.04.5 LTS for me) to 18.04 (18.04.1 LTS in fact), we must confirm the "Notify me of a new Ubuntu version:" option is set to "For any new version", and change it if otherwise.
My question is : why not to keep it set at its default value, which is : "For long-term support versions" ? 18.04(.1) is indeed an LTS version ! So this option should also enable the migration.
I have another question: in addition to allowing the change from 16.04(.5) to 18.04(.1), what are/will be the other (potentially bad) consequences of choosing the "For any new version" option, recommended by the above documentation?
Am I making a mistake ?
This migration is really impossible when "For long term support versions" is chosen. It's possible when "For any new version" is chosen.