I have tried this below.
Press Ctrl+Alt+T to open a terminal.
Type the command sudo nano /etc/apt/sources.list . In this file, search for vivaldi repository.
Now, replace the line with:
deb [trusted=yes] https://repo.vivaldi.com/archive/deb/ stable main Now, press Ctrl+X followed by y and then Enter to save the files.
Finally, update the package list:
sudo apt update
But i get this then
Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:2 http://se.archive.ubuntu.com/ubuntu eoan InRelease
Hit:3 http://ppa.launchpad.net/git-core/ppa/ubuntu eoan InRelease
Hit:4 http://se.archive.ubuntu.com/ubuntu eoan-updates InRelease
Hit:5 http://se.archive.ubuntu.com/ubuntu eoan-backports InRelease
Get:6 http://security.ubuntu.com/ubuntu eoan-security InRelease [97,5 kB]
Hit:7 https://dl.winehq.org/wine-builds/ubuntu eoan InRelease
Hit:8 http://dl.google.com/linux/chrome/deb stable Release
Hit:9 https://deb.nodesource.com/node_12.x eoan InRelease
Hit:10 http://ppa.launchpad.net/kritalime/ppa/ubuntu eoan InRelease
Hit:11 http://archive.canonical.com/ubuntu disco InRelease
Hit:12 https://deb.torproject.org/torproject.org eoan InRelease
Ign:13 https://repo.vivaldi.com/archive/deb stable InRelease
Hit:14 https://cli-assets.heroku.com/apt ./ InRelease
Hit:15 http://ppa.launchpad.net/linrunner/tlp/ubuntu eoan InRelease
Get:16 http://security.ubuntu.com/ubuntu disco-security InRelease [97,5 kB]
Ign:17 https://repo.vivaldi.com/archive/deb stable Release
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Hit:19 https://download.sublimetext.com apt/stable/ InRelease
Ign:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Hit:22 https://packagecloud.io/AtomEditor/atom/any any InRelease
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Ign:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Ign:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Get:32 http://security.ubuntu.com/ubuntu eoan-security/main amd64 DEP-11 Metadata [204 B]
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Get:33 http://security.ubuntu.com/ubuntu eoan-security/universe amd64 DEP-11 Metadata [1 672 B]
Get:34 http://security.ubuntu.com/ubuntu eoan-security/universe DEP-11 48x48 Icons [7 096 B]
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Get:35 http://security.ubuntu.com/ubuntu eoan-security/universe DEP-11 64x64 Icons [6 242 B]
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Ign:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Ign:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Ign:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Ign:18 https://repo.vivaldi.com/archive/deb stable/main all Packages
Err:20 https://repo.vivaldi.com/archive/deb stable/main i386 Packages
Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 23.111.9.47 443]
Ign:21 https://repo.vivaldi.com/archive/deb stable/main amd64 Packages
Ign:23 https://repo.vivaldi.com/archive/deb stable/main Translation-en
Ign:24 https://repo.vivaldi.com/archive/deb stable/main Translation-en_US
Ign:25 https://repo.vivaldi.com/archive/deb stable/main all DEP-11 Metadata
Ign:26 https://repo.vivaldi.com/archive/deb stable/main amd64 DEP-11 Metadata
Ign:27 https://repo.vivaldi.com/archive/deb stable/main DEP-11 48x48 Icons
Ign:28 https://repo.vivaldi.com/archive/deb stable/main DEP-11 64x64 Icons
Ign:29 https://repo.vivaldi.com/archive/deb stable/main amd64 c-n-f Metadata
Ign:30 https://repo.vivaldi.com/archive/deb stable/main all c-n-f Metadata
Fetched 210 kB in 16s (13,4 kB/s)
Reading package lists... Done
E: Failed to fetch https://repo.vivaldi.com/archive/deb/dists/stable/main/binary-i386/Packages Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 23.111.9.47 443]
E: Some index files failed to download. They have been ignored, or old ones used instead.
What can i do to resolve these two issues
Here is my file nano /etc/apt/sources.list
# deb cdrom:[Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ di>
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://se.archive.ubuntu.com/ubuntu/ eoan main restricted
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://se.archive.ubuntu.com/ubuntu/ eoan-updates main restricted
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://se.archive.ubuntu.com/ubuntu/ eoan universe
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco universe
deb http://se.archive.ubuntu.com/ubuntu/ eoan-updates universe
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://se.archive.ubuntu.com/ubuntu/ eoan multiverse
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco multiverse
deb http://se.archive.ubuntu.com/ubuntu/ eoan-updates multiverse
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://se.archive.ubuntu.com/ubuntu/ eoan-backports main restricted univers>
# deb-src http://se.archive.ubuntu.com/ubuntu/ disco-backports main restricted >
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu disco partner
deb-src http://archive.canonical.com/ubuntu disco partner
deb http://security.ubuntu.com/ubuntu eoan-security main restricted
deb-src http://security.ubuntu.com/ubuntu disco-security main restricted
deb http://security.ubuntu.com/ubuntu eoan-security universe
deb-src http://security.ubuntu.com/ubuntu disco-security universe
deb http://security.ubuntu.com/ubuntu eoan-security multiverse
deb-src http://security.ubuntu.com/ubuntu disco-security multiverse
# deb [arch=amd64] https://download.docker.com/linux/ubuntu eoan stable # disab>
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu disco stable
deb [arch=amd64] https://packagecloud.io/AtomEditor/atom/any/ any main # disabl>
deb-src [arch=amd64] https://packagecloud.io/AtomEditor/atom/any/ any main
# deb https://cli-assets.heroku.com/branches/stable/apt ./ # disabled on upgrad>
deb-src http://security.ubuntu.com/ubuntu disco-security multiverse
# deb [arch=amd64] https://download.docker.com/linux/ubuntu eoan stable # disab>
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu disco stable
deb [arch=amd64] https://packagecloud.io/AtomEditor/atom/any/ any main # disabl>
deb-src [arch=amd64] https://packagecloud.io/AtomEditor/atom/any/ any main
# deb https://cli-assets.heroku.com/branches/stable/apt ./ # disabled on upgrad>
# deb-src https://cli-assets.heroku.com/branches/stable/apt ./
deb https://deb.torproject.org/torproject.org eoan main # disabled on upgrade t>
deb https://dl.winehq.org/wine-builds/ubuntu/ eoan main # disabled on upgrade t>
# deb-src https://dl.winehq.org/wine-builds/ubuntu/ disco main
# deb [trusted=yes] https://repo.vivaldi.com/archive/deb/ stable main # disable>
# deb-src https://repo.vivaldi.com/deb [trusted=yes] https://repo.vivaldi.com/a>
# deb-src https://repo.vivaldi.com/archive/deb/ stable main
# deb-src [arch=amd64] https://packages.microsoft.com/repos/vscode stable main
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu disco stable
# deb [arch=amd64] https://download.docker.com/linux/ubuntu disco stable
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu disco stable
# deb-src https://dl.winehq.org/wine-builds/ubuntu/ eoan main
# deb-src https://repo.vivaldi.com/archive/deb/ stable main
E: Failed to fetch 1)
https://repo.vivaldi.com/archive/deb/dists/stable/main/binary-i386/Packages Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 23.111.9.47 443] E: Some index files failed to download. They have been ignored, or old ones used instead.
2)
Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 23.111.9.47 443]
The current Vivaldi website certificate for repo.vivaldi.com expired on Jan 2, 2020, so you cannot use https to connect it anymore.
This is not a fault with your system.
It's a fault with the Vivaldi website. Only they can fix it. Feel free to let the Vivaldi folks know about the problem with their website.