[Solved][Linux Mint] An error occurred during the signature verification

If you run into the dreaded key error “An error occurred during the signature verification” or “The following signatures couldn’t be verified because the public key is not available” in debian linux while adding repositories that have different keys for different versions. Like the palemoon repository contains different keys for 20.10, 20.04, 18.04. Hopefully, this solution will help you.

1. Go to the gpg directory and delete the key that’s been causing you trouble. The directory contains the list of keys that your system trusts.

/etc/apt/trusted.gpg.d/


2. Open a terminal on this folder, then delete the offending key files.

sudo rm -v home_stevenpusser.*


3. Then run the installation commands including downloading and adding new keys. You might also need to run a command to manually add the keys to the keyring.

sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys <hex_key>


Then that's it. try to install the application again after running:

sudo apt update
That's it. It should start validating signatures without running into the errors again.