Unable to update Plesk: The following signatures couldn’t be verified because the public key is not available

Symptoms

• Unable to update Plesk, the process fails with the following error also found at /var/log/plesk/install/autoinstaller3.log:

  GPG error: http://autoinstall.plesk.com jessie InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY BD11A6AA914BDF7E

Cause

Plesk GPG key is not installed.

Resolution

1. Log into the server via SSH.

2. Fetch and install the missing GPG key:

   • For CentOS/RHEL:

     # rpm --import http://autoinstall.plesk.com/plesk.gpg

   • For Debian/Ubuntu:

     # wget http://autoinstall.plesk.com/plesk.gpg && apt-key add plesk.gpg