mint@mint:~$ sudo apt update
Ign:1 cdrom://Linux Mint 20 _Ulyana_ - Release amd64 20200624 focal InRelease
Err:2 cdrom://Linux Mint 20 _Ulyana_ - Release amd64 20200624 focal Release
  Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Ign:3 http://packages.linuxmint.com ulyana InRelease
Get:4 http://security.ubuntu.com/ubuntu focal-security InRelease [107 kB]
Get:5 http://packages.linuxmint.com ulyana Release [24.1 kB]
Hit:6 http://archive.ubuntu.com/ubuntu focal InRelease
Get:7 http://archive.canonical.com/ubuntu focal InRelease [12.1 kB]
Get:8 http://archive.ubuntu.com/ubuntu focal-updates InRelease [111 kB]
Get:9 http://packages.linuxmint.com ulyana Release.gpg [819 B]
Get:10 http://archive.canonical.com/ubuntu focal/partner amd64 Packages [1600 B]
Get:11 http://security.ubuntu.com/ubuntu focal-security/main i386 Packages [145 kB]
Get:12 http://packages.linuxmint.com ulyana/main i386 Packages [13.6 kB]
Get:13 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages [348 kB]
Get:14 http://packages.linuxmint.com ulyana/main amd64 Packages [14.2 kB]
Get:15 http://archive.ubuntu.com/ubuntu focal-backports InRelease [98.3 kB]
Get:16 http://security.ubuntu.com/ubuntu focal-security/main Translation-en [79.6 kB]
Get:17 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages [631 kB]
Get:18 http://security.ubuntu.com/ubuntu focal-security/main amd64 DEP-11 Metadata [24.3 kB]
Get:19 http://packages.linuxmint.com ulyana/upstream amd64 Packages [38.5 kB]
Get:20 http://security.ubuntu.com/ubuntu focal-security/restricted amd64 Packages [66.0 kB]
Get:21 http://security.ubuntu.com/ubuntu focal-security/restricted i386 Packages [8920 B]
Get:22 http://security.ubuntu.com/ubuntu focal-security/restricted Translation-en [10.9 kB]
Get:23 http://security.ubuntu.com/ubuntu focal-security/universe i386 Packages [408 kB]
Get:24 http://security.ubuntu.com/ubuntu focal-security/universe amd64 Packages [515 kB]
Get:25 http://packages.linuxmint.com ulyana/upstream i386 Packages [10.4 kB]
Get:26 http://packages.linuxmint.com ulyana/import amd64 Packages [7535 B]
Get:27 http://packages.linuxmint.com ulyana/backport amd64 Packages [29.9 kB]
Get:28 http://packages.linuxmint.com ulyana/backport i386 Packages [6319 B]
Get:29 http://security.ubuntu.com/ubuntu focal-security/universe Translation-en [65.9 kB]
Get:30 http://security.ubuntu.com/ubuntu focal-security/universe amd64 DEP-11 Metadata [55.7 kB]
Get:31 http://security.ubuntu.com/ubuntu focal-security/multiverse amd64 Packages [1256 B]
Get:32 http://security.ubuntu.com/ubuntu focal-security/multiverse Translation-en [540 B]
Get:33 http://archive.ubuntu.com/ubuntu focal-updates/main i386 Packages [362 kB]
Get:34 http://archive.ubuntu.com/ubuntu focal-updates/main Translation-en [159 kB]
Get:35 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 DEP-11 Metadata [229 kB]
Get:36 http://archive.ubuntu.com/ubuntu focal-updates/restricted amd64 Packages [78.7 kB]
Get:37 http://archive.ubuntu.com/ubuntu focal-updates/restricted i386 Packages [12.0 kB]
Get:38 http://archive.ubuntu.com/ubuntu focal-updates/restricted Translation-en [12.5 kB]
Get:39 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages [683 kB]
Get:40 http://archive.ubuntu.com/ubuntu focal-updates/universe i386 Packages [509 kB]
Get:41 http://archive.ubuntu.com/ubuntu focal-updates/universe Translation-en [131 kB]
Get:42 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 DEP-11 Metadata [204 kB]
Get:43 http://archive.ubuntu.com/ubuntu focal-updates/multiverse amd64 Packages [15.1 kB]
Get:44 http://archive.ubuntu.com/ubuntu focal-updates/multiverse i386 Packages [4372 B]
Get:45 http://archive.ubuntu.com/ubuntu focal-updates/multiverse Translation-en [3892 B]
Get:46 http://archive.ubuntu.com/ubuntu focal-updates/multiverse amd64 DEP-11 Metadata [2468 B]
Get:47 http://archive.ubuntu.com/ubuntu focal-backports/universe i386 Packages [2904 B]
Get:48 http://archive.ubuntu.com/ubuntu focal-backports/universe amd64 Packages [4012 B]
Get:49 http://archive.ubuntu.com/ubuntu focal-backports/universe Translation-en [1448 B]
Get:50 http://archive.ubuntu.com/ubuntu focal-backports/universe amd64 DEP-11 Metadata [1768 B]
Reading package lists... Done
E: The repository 'cdrom://Linux Mint 20 _Ulyana_ - Release amd64 20200624 focal Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.