An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://brave-browser-apt-release.s3.brave.com bionic InRelease: The following signatures couldn't be verified because

[smersh2]

Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease Ign:2 http://dl.google.com/linux/chrome/deb stable InRelease Hit:3 http://archive.canonical.com/ubuntu bionic InRelease Ign:4 http://liveusb.info/multisystem/depot all InRelease Hit:5 http://ppa.launchpad.net/alex-p/aegisub/ubuntu bionic InRelease Get:6 http://security.ubuntu.com/ubuntu bionic-security InRelease [83.2 kB] Get:7 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB] Hit:8 https://download.virtualbox.org/virtualbox/debian bionic InRelease Hit:9 http://liveusb.info/multisystem/depot all Release Hit:10 http://dl.google.com/linux/chrome/deb stable Release Hit:11 http://ppa.launchpad.net/daniel-marynicz/filemanager-actions/ubuntu bionic InRelease Ign:12 http://apt.izzysoft.de/ubuntu generic InRelease Hit:13 https://deb.opera.com/opera-stable stable InRelease Ign:15 http://packages.linuxmint.com tara InRelease Get:16 https://brave-browser-apt-release.s3.brave.com bionic InRelease [3,169 B] Hit:17 http://ppa.launchpad.net/danielrichter2007/grub-customizer/ubuntu bionic InRelease Get:18 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB] Hit:19 http://packages.linuxmint.com tara Release Hit:20 http://ppa.launchpad.net/dreibh/ppa/ubuntu bionic InRelease Hit:21 http://ppa.launchpad.net/gerardpuig/ppa/ubuntu bionic InRelease Hit:14 https://apt.izzysoft.de/ubuntu generic Release Hit:22 https://repo.windscribe.com/ubuntu zesty InRelease Hit:23 http://ppa.launchpad.net/pedrocastro/ppa/ubuntu bionic InRelease Hit:25 http://ppa.launchpad.net/rodsmith/refind/ubuntu bionic InRelease Hit:27 http://ppa.launchpad.net/ufleisch/kid3/ubuntu bionic InRelease Hit:28 http://ppa.launchpad.net/webupd8team/java/ubuntu bionic InRelease Err:16 https://brave-browser-apt-release.s3.brave.com bionic InRelease

The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 0B31DBA06A8A26F9
Fetched 247 kB in 3s (89.0 kB/s)
Reading package lists…

[Declanomad]

Same error here on Linux Mint.
I installed BRAVE a week ago following the install instructions for linux on the website.

Below - Error message from Mint Update Manager

An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://brave-browser-apt-release.s3.brave.com xenial InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 0B31DBA06A8A26F9Failed to fetch https://brave-browser-apt-release.s3.brave.com/dists/xenial/InRelease The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 0B31DBA06A8A26F9Some index files failed to download. They have been ignored, or old ones used instead.

[vvv]

To remedy this issue, re-run the apt-key add command from the install instruction found here:

https://brave-browser.readthedocs.io/en/latest/installing-brave.html#linux

specifically, at the time of this writing:
curl -s https://brave-browser-apt-release.s3.brave.com/brave-core.asc | sudo apt-key add -

[th1gr8scott]

I followed the instructions for the provided link and I an still having the same problem. I too only installed Brave a few days ago on a newly installed Linux Mint system. Any other suggestions will be greatly appreciated.

Thanks,