J'ai nettoyé et pour le source.list j'obtiens
/etc/apt/sources.list
1 # deb cdrom:[Ubuntu 18.04 _Bionic_ - Build amd64 LIVE Binary 20190418-12:10]/ bionic main
2
3 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
4 # newer versions of the distribution.
5 deb http://fr.archive.ubuntu.com/ubuntu/ focal main restricted
6 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic main restricted
7
8 ## Major bug fix updates produced after the final release of the
9 ## distribution.
10 deb http://fr.archive.ubuntu.com/ubuntu/ focal-updates main restricted
11 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
12
13 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
14 ## team. Also, please note that software in universe WILL NOT receive any
15 ## review or updates from the Ubuntu security team.
16 deb http://fr.archive.ubuntu.com/ubuntu/ focal universe
17 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic universe
18 deb http://fr.archive.ubuntu.com/ubuntu/ focal-updates universe
19 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic-updates universe
20
21 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
22 ## team, and may not be under a free licence. Please satisfy yourself as to
23 ## your rights to use the software. Also, please note that software in
24 ## multiverse WILL NOT receive any review or updates from the Ubuntu
25 ## security team.
26 deb http://fr.archive.ubuntu.com/ubuntu/ focal multiverse
27 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic multiverse
28 deb http://fr.archive.ubuntu.com/ubuntu/ focal-updates multiverse
29 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
30
31 ## N.B. software from this repository may not have been tested as
32 ## extensively as that contained in the main release, although it includes
33 ## newer versions of some applications which may provide useful features.
34 ## Also, please note that software in backports WILL NOT receive any review
35 ## or updates from the Ubuntu security team.
36 deb http://fr.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
37 # deb-src http://fr.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
38
39 ## Uncomment the following two lines to add software from Canonical's
40 ## 'partner' repository.
41 ## This software is not part of Ubuntu, but is offered by Canonical and the
42 ## respective vendors as a service to Ubuntu users.
43 deb http://archive.canonical.com/ubuntu focal partner
44 # deb-src http://archive.canonical.com/ubuntu bionic partner
45
46 deb http://security.ubuntu.com/ubuntu focal-security main restricted
47 # deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
48 deb http://security.ubuntu.com/ubuntu focal-security universe
49 # deb-src http://security.ubuntu.com/ubuntu bionic-security universe
50 deb http://security.ubuntu.com/ubuntu focal-security multiverse
51 # deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse
/etc/apt/sources.list.d/deadsnakes-ubuntu-ppa-focal.list
1 # deb-src http://ppa.launchpad.net/deadsnakes/ppa/ubuntu focal main
/etc/apt/sources.list.d/steam.list
1 deb [arch=amd64,i386] https://repo.steampowered.com/steam/ stable steam
2 deb-src [arch=amd64,i386] https://repo.steampowered.com/steam/ stable steam
3
4 # Uncomment these lines to try the beta version of the Steam launcher
5 #deb [arch=amd64,i386] https://repo.steampowered.com/steam/ beta steam
6 #deb-src [arch=amd64,i386] https://repo.steampowered.com/steam/ beta steam
/etc/apt/sources.list.d/bionic-dell.list
1 # deb http://dell.archive.canonical.com/updates/ bionic-dell public # désactivé pour la mise à niveau vers focal
2 # deb-src http://dell.archive.canonical.com/updates/ bionic-dell public
/etc/apt/sources.list.d/bionic-oem.list
1 # deb http://oem.archive.canonical.com/updates/ bionic-oem public # désactivé pour la mise à niveau vers focal
2 # deb-src http://oem.archive.canonical.com/updates/ bionic-oem public
/etc/apt/sources.list.d/bionic-dell-beaver-osp1-maester.list
1 # deb http://dell.archive.canonical.com/updates/ bionic-dell-beaver-osp1-maester public # désactivé pour la mise à niveau vers focal
2 # deb-src http://dell.archive.canonical.com/updates/ bionic-dell-beaver-osp1-maester public
/etc/apt/sources.list.d/google-chrome.list
1 ### THIS FILE IS AUTOMATICALLY CONFIGURED ###
2 # You may comment out this entry, but any other modifications may be lost.
3 # deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main # désactivé pour la mise à niveau vers focal
/etc/apt/sources.list.d/obsproject-ubuntu-obs-studio-focal.list
1 deb http://ppa.launchpad.net/obsproject/obs-studio/ubuntu focal main
2 # deb-src http://ppa.launchpad.net/obsproject/obs-studio/ubuntu focal main
/etc/apt/sources.list.d/bionic-dell-service.list
1 # deb http://dell.archive.canonical.com/updates/ bionic-dell-service public # désactivé pour la mise à niveau vers focal
2 # deb-src http://dell.archive.canonical.com/updates/ bionic-dell-service public
/etc/apt/sources.list.d/deadsnakes-ubuntu-ppa-bionic.list
1 deb http://ppa.launchpad.net/deadsnakes/ppa/ubuntu focal main # désactivé pour la mise à niveau vers focal
2 # deb-src http://ppa.launchpad.net/deadsnakes/ppa/ubuntu bionic main
