Fix “The following signatures couldn’t be verified” : Ubuntu 22.04 GPG error

The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8539176957BCBAF6
Reading package lists... Done
W: GPG error: http://ppa.launchpad.net/peek-developers/daily/ubuntu jammy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8539176957BCBAF6

This is the common error that you will come across on Ubuntu 22.04 LTS while  attempting to include third-party package repositories to the apt package manager.

Fix “The following signatures couldn’t be verified”: Ubuntu 22.04 GPG error

It’s pretty simple to fix this error as we will go through the process to import public-key signatures and other process to fix Fix “The following signatures couldn’t be verified”: Ubuntu 22.04 GPG

In this error, you need to figure out the Public key

The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8539176957BCBAF6 Reading package lists... Done W: GPG error: http://ppa.launchpad.net/peek-developers/daily/ubuntu jammy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8539176957BCBAF6 error.

Here the public key is 8539176957BCBAF6.

Now run the following command to import the public key to the Ubuntu 22.04 system by using the apt-key command. Example:

$ sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 8539176957BCBAF6
Executing: /tmp/apt-key-gpghome.fnm4L3G3iP/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 8539176957BCBAF6
gpg: key 8539176957BCBAF6: public key "Launchpad PPA for Peek Developers" imported
gpg: Total number processed: 1
gpg:               imported: 1

Now, run the following command to confirm that the public key has been imported.

$ apt-key list
/etc/apt/trusted.gpg
--------------------
pub   rsa4096 2017-02-14 [SC]
      8C95 3129 9E7D F2DC F681  B499  8539 1769 57BC BAF6
uid           [ unknown] Launchpad PPA for Peek Developers

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-archive.gpg
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