Unable to edit 'cdrom' repository on Ubuntu 16.10

[lcorreia]

Trying to edit the 'cdrom' repository automatically created by distro, I got the following errors:
GGBREPOS0002E: Repository URL must be an http://, ftp:// or file:// URL.
GGBREPOS0002E: Repository URL must be an http://, ftp:// or file:// URL.
GGBREPOS0012E: Repository [Ubuntu-Server 16.10 Yakkety Yak - Release amd64 (20161012.1)]/-yakkety-main-restricted does not exist.

Afterwards, I couldn't find the same repository listed in UI. It seems it was deleted after I canceled edition.