title: mixed content error with custom font that doesn't exist anymore
body: <p>I have multilingual site, I install ssl recently(with let's encrypt), and used some plugin like really simple ssl, ssl insecure content fixer, http/https remover to fix mixed content error but none of these plugin did not fixed the problem. the I use google dev-tools, and see 6 mixed content error like this from 3 custom font, that doesn't exist anymore (i delete them):</p>
  
  <pre><code>Mixed Content: The page at 'https://www.safeducation.com/' was loaded over HTTPS, but requested an insecure font 'http://safeducation.com/wp-content/uploads/avia_fonts/type_fonts/yekan/yekan.ttf'. This request has been blocked; the content must be served over HTTPS.
  </code></pre>
  
  <p>I connected to host via ftp and ../wp-content/uploads/avia_fonts/type_fonts/ directory was empty. there was no other folder.</p>
  
  <p>I downloaded the root directory to my host and search with atom, to find any <a href="http://saf" rel="nofollow noreferrer">http://saf</a>... and change them in host but the problem still did not resolve</p>
  
  <p>I'm confused because there was no any folder in ../wp-content/uploads/avia_fonts/type_fonts
  can anyone help me, what should I do to fix this problem?
  thanks for your time</p>