You can confirm the release you originally installed on the system by looking at /var/log/installer/media-info. An example:
$ cat /var/log/installer/media-info Ubuntu-Server 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
You can confirm the release you originally installed on the system by looking at /var/log/ installer/ media-info. An example:
$ cat /var/log/ installer/ media-info
Ubuntu-Server 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)