title: 'sudo apt-get update' failure
body: <p>Below is the o/p for <code>sudo apt-get update</code>:</p>
  
  <pre><code>/etc/apt$ sudo apt-get update
  Get:1 http://01.archive.ubuntu.com/ubuntu bionic InRelease [242 kB]
  Err:1 http://01.archive.ubuntu.com/ubuntu bionic InRelease
    The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32
  Get:2 http://01.archive.ubuntu.com/ubuntu bionic-security InRelease [83.2 kB]
  Err:2 http://01.archive.ubuntu.com/ubuntu bionic-security InRelease
    The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32
  Get:3 http://01.archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]
  Err:3 http://01.archive.ubuntu.com/ubuntu bionic-updates InRelease
    The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32
  Reading package lists... Done
  W: GPG error: http://01.archive.ubuntu.com/ubuntu bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32
  E: The repository 'http://01.archive.ubuntu.com/ubuntu bionic InRelease' is not signed.
  N: Updating from such a repository can't be done securely, and is therefore disabled by default.
  N: See apt-secure(8) manpage for repository creation and user configuration details.
  W: GPG error: http://01.archive.ubuntu.com/ubuntu bionic-security InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32
  E: The repository 'http://01.archive.ubuntu.com/ubuntu bionic-security InRelease' is not signed.
  N: Updating from such a repository can't be done securely, and is therefore disabled by default.
  N: See apt-secure(8) manpage for repository creation and user configuration details.
  W: GPG error: http://01.archive.ubuntu.com/ubuntu bionic-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY &lt;Pub_key_here&gt;
  E: The repository 'http://01.archive.ubuntu.com/ubuntu bionic-updates InRelease' is not signed.
  N: Updating from such a repository can't be done securely, and is therefore disabled by default.
  N: See apt-secure(8) manpage for repository creation and user configuration details.
  </code></pre>
  
  <p>All <code>install</code> commands failing because of this I believe. </p>
  
  <p>I would just like to reset things back to normal as I messed this while uninstalling virtualbox,kubectl. I was just getting familiar with that. Experiment back fired.</p>
  
  <p>I've tried replacing <code>sources.list</code> using <a href="https://repogen.simplylinux.ch/generate.php" rel="nofollow noreferrer">this</a> among other things I tried.</p>
  
  <p>Any help is appreciated.</p>