title: How to fix "invalid signature when apt-get update" error?
body: <p>Whenever I'm trying to <code>sudo apt-get update</code> I'm getting these errors:</p>
  <pre><code>W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://packages.linuxmint.com rafaela Release: The following signatures were invalid: BADSIG 3EE67F3D0FF405B2 Clement Lefebvre (Linux Mint Package Repository v1) &lt;root@linuxmint.com&gt;
  
  W: GPG error: http://extra.linuxmint.com rafaela Release: The following signatures were invalid: BADSIG 3EE67F3D0FF405B2 Clement Lefebvre (Linux Mint Package Repository v1) &lt;root@linuxmint.com&gt;
  W: Failed to fetch http://packages.linuxmint.com/dists/rafaela/Release  
  
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/trusty/Release  Unable to find expected entry 'restricted/binary-amd64/Packages' in Release file (Wrong sources.list entry or malformed file)
  
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/trusty/main/binary-amd64/Packages  Hash Sum mismatch
  
  W: Some index files failed to download. They have been ignored, or old ones used instead.
  </code></pre>
  <p>So, I did some reading and tried changing mirrors in the sofetware-sources area, and also followed this <a href="https://unix.stackexchange.com/questions/97493/invalid-signatures-when-running-apt-get-update">answer</a>, and ran this command:</p>
  <p><code>sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 3EE67F3D0FF405B2</code></p>
  <p>but got this result which didn't help me:</p>
  <pre><code>Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.joWxQNcMmd --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --recv-keys --keyserver keyserver.ubuntu.com 3EE67F3D0FF405B2
  gpg: requesting key 0FF405B2 from hkp server keyserver.ubuntu.com
  gpg: key 0FF405B2: &quot;Clement Lefebvre (Linux Mint Package Repository v1) &lt;root@linuxmint.com&gt;&quot; not changed
  gpg: Total number processed: 1
  gpg:              unchanged: 1
  </code></pre>
  <p>Any idea what else I can try in order to solve it?</p>
  <p>p.s It all started when trying to install nodejs and npm.</p>