Keyring problem

[#&thj^%]

Looks like that repository in your sources list uses the Signed-By option multiple times, so apt doesn't know which key to use to check the signature. Or maybe it's a related problem, but there seems to be a case of conflicting keys.

When we encounter the error, it’s usually because apt has found multiple conflicting instructions regarding the GPG key to verify a particular repository.

Specifically, this conflict arises from duplicated repository entries, incorrect or outdated GPG keys, or improperly configured repository settings.

I think currentshaft is on track, I'll go away now...Good Luck

[#&thj^%]

I am logged in as root while doing that...

That would have been good to know before hand, is it any different as your normal user?

EDIT: Can you show us this:

ls /etc/apt/keyrings/

[#&thj^%]

Ok I'll start from the beginning for Opera

sudo apt install dirmngr ca-certificates software-properties-common apt-transport-https curl -y

Now import its GPG key

curl -fsSL https://deb.opera.com/archive.key | gpg --dearmor | sudo tee /usr/share/keyrings/opera.gpg > /dev/null

I'll add the Opera Browser’s APT repository
[code]
Add the source

echo deb [arch=amd64 signed-by=/usr/share/keyrings/opera.gpg] https://deb.opera.com/opera-stable/ stable non-free | sudo tee /etc/apt/sources.list.d/opera.list

install time:

sudo apt update 
sudo apt install opera-stable

I used it for couple minutes then I purged it:

sudo apt autoremove --purge opera-stable
REMOVING:                       
  chromium-codecs-ffmpeg-extra*  opera-stable*

Summary:
  Upgrading: 0, Installing: 0, Removing: 2, Not Upgrading: 0
  Freed space: 320 MB

Continue? [Y/n] 
(Reading database ... 399641 files and directories currently installed.)
Removing chromium-codecs-ffmpeg-extra (2:1snap1-0ubuntu2) ...
Removing opera-stable (112.0.5197.39) ...
Processing triggers for hicolor-icon-theme (0.18-1) ...
Processing triggers for gnome-menus (3.36.0-1.1ubuntu3) ...
Processing triggers for shared-mime-info (2.4-5) ...
Processing triggers for menu (2.1.50) ...
Processing triggers for desktop-file-utils (0.27-2build1) ...
(Reading database ... 399469 files and directories currently installed.)
Purging configuration files for opera-stable (112.0.5197.39) ...
Processing triggers for menu (2.1.50) ...

I'll look here:

ls /usr/share/keyrings/opera.gpg
/usr/share/keyrings/opera.gpg

I want that gone too:

 sudo rm -r /usr/share/keyrings/opera.gpg

Now:

ls /usr/share/keyrings/opera.gpg
ls: cannot access '/usr/share/keyrings/opera.gpg': No such file or directory

Now back to normal:

 ls /usr/share/keyrings/
brave-browser-archive-keyring.gpg          ubuntu-pro-anbox-cloud.gpg
brave-browser-beta-archive-keyring.gpg     ubuntu-pro-cc-eal.gpg
brave-browser-nightly-archive-keyring.gpg  ubuntu-pro-cis.gpg
protonvpn-stable-archive-keyring.gpg       ubuntu-pro-esm-apps.gpg
ubuntu-archive-keyring.gpg                 ubuntu-pro-esm-infra.gpg
ubuntu-archive-removed-keys.gpg            ubuntu-pro-fips.gpg
ubuntu-cloudimage-keyring.gpg              ubuntu-pro-fips-preview.gpg
ubuntu-cloudimage-removed-keys.gpg         ubuntu-pro-realtime-kernel.gpg
ubuntu-master-keyring.gpg                  ubuntu-pro-ros.gpg

[Pierre Dartigues]

There is no response:

Asus:~$ ls /etc/apt/keyrings/
Asus:~$

[Pierre Dartigues]

These are the responses I get from the proposed entries:

root@Asus:~# sudo apt install dirmngr ca-certificates software-properties-common apt-transport-https curl -y
E: Conflicting values set for option Signed-By regarding source https://deb.opera.com/opera-stable/ stable: /usr/share/keyrings/opera-browser.gpg != /usr/share/keyrings/opera.gpg
E: The list of sources could not be read.

root@Asus:~# curl -fsSL https://deb.opera.com/archive.key | gpg --dearmor | sudo tee /usr/share/keyrings/opera.gpg > /dev/null
root@Asus:~#

root@Asus:~# echo deb [arch=amd64 signed-by=/usr/share/keyrings/opera.gpg] https://deb.opera.com/opera-stable/ stable non-free | sudo tee /etc/apt/sources.list.d/opera.list
deb [arch=amd64 signed-by=/usr/share/keyrings/opera.gpg] https://deb.opera.com/opera-stable/ stable non-free
root@Asus:~#



root@Asus:~# sudo apt update
E: Conflicting values set for option Signed-By regarding source https://deb.opera.com/opera-stable/ stable: /usr/share/keyrings/opera-browser.gpg != /usr/share/keyrings/opera.gpg
E: The list of sources could not be read.
root@Asus:~#

But: Somehow my trial removing the opera-files from

/etc/apt/sources.list.d

succeeded. I ignore why now it worked an earliar it did not...
I will try out what happens now after I performed a reboot.

[Pierre Dartigues]

After that I have been able to remove successfully the opera* files from

/etc/apt/sources.list.d

all of the commands you proposed in #13 succeeded and I was able to install new software again.
I am very grateful for your help, I have been coping with this problem for at least three months and now it's solved.
Thanks a lot!

[#&thj^%]

Great News. Happy to hear that.
As a help to others please mark as Solved.