OS version is 5.1.7 Hera. I got the following error when I try to update in app center:

- W: GPG error: http://repo.vivaldi.com/stable/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 793FEB8BB69735B2
- E: The repository 'http://repo.vivaldi.com/stable/deb stable Release' is not signed.
- 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.

Since the problem seem to be vivaldi, I tried to remove it (I don't use it anyway) using sudo apt purge vivaldi, sudo apt-get purge-vivaldi-stable, and dpkg -l | grep vivaldi. After that I tried to update again, but the error persist.

I also tried to try to import all missing GPG keys using y-ppa-manager, but the error still persist.

I don't understand how to fix it, so any help will be appreciated. Sorry for the trouble and thank you.


1 Answer 1


Just remove the repo for your system:

sudo rm /etc/apt/sources.list.d/vivaldi.list

I hope this help you


Could you please try: cd ~ wget https://repo.vivaldi.com/stable/linux_signing_key.pub sudo apt-key add linux_signing_key.pub

  • I tried that, and the terminal said: rm: cannot remove '/etc/apt/sources.list.d/vivaldi.list': No such file or directory And the 'failed to fecth updates' still persist.
    – fk20
    Jan 11, 2021 at 9:07
  • 1
    I modified the answer, please try again. best regards. Jan 12, 2021 at 2:34
  • Ok, I tried it and it works! Thank you so much!
    – fk20
    Jan 12, 2021 at 10:39

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