I recently upgraded an Ubuntu box from 10.04 to 11.10. During the upgrade process, all of the accounts except the one I created on installation were lost, and had to be recovered. Subsequently, I upgraded the SAME box to 12.04 from 11.10, and the accounts remained. I'm wondering why this is. Did something change from 10.x to 11.x/12.x? I think that Ubuntu may have switched to GNOME 3... I'm just wondering why it only happened in the first case.
What you observed is the expected behaviour.
We are only able to upgrade from one release to the next or from an LTS-release to the next LTS-release without losing user settings and accounts. All other "upgrades" are basically a new installation but without erasing our
/home directory. Accounts and applications will have to be set up again then.
If you had upgraded from 10.04 LTS to 12.04 LTS as a proper upgrade path your accounts would have been preserved. With an interim upgrade via 11.10 this was not possible.
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