Fix : GPG error - Signature invalid ( BADSIG )

Assalamualaikum dan salam sejahtera kepada semua peminat sistem operasi Linux/GNU. Kadang-kadang bila kita nak kemaskini dengan arahan sudo apt-get update , kita akan dapat maklumat ralat GPG error dan BADSIG seperti dibawah :

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Reading package lists... Done
W: GPG error: http://dl.google.com stable Release: The following signatures were invalid: BADSIG A040830F7FAC5991 Google, Inc. Linux Package Signing Key <linux-packages-keymaster@google.com>
W: GPG error: http://archive.canonical.com raring Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
W: GPG error: http://ppa.launchpad.net raring Release: The following signatures were invalid: BADSIG B22A95F88110A93A Launchpad PPA for Bumlebee Project
W: GPG error: http://ppa.launchpad.net raring Release: The following signatures were invalid: BADSIG D530E028F59EAE4D Launchpad PPA for NoobsLab
W: GPG error: http://ppa.launchpad.net raring Release: The following signatures were invalid: BADSIG FC6D7D9D009ED615 Launchpad PPA for Shutter Team
W: GPG error: http://ppa.launchpad.net raring Release: The following signatures were invalid: BADSIG 3B22AB97AF1CDFA9 Launchpad PPA for Ubuntu-X
W: GPG error: http://ppa.launchpad.net raring Release: The following signatures were invalid: BADSIG C2518248EEA14886 Launchpad VLC

Cara paling mudah untuk menyelesaikan masalah ini ialah dengan menukarkan sahaja senarai pakej yang baru (jalankan arahan sebagai mod root):

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update

Selamat mencuba. Wassalam~