&quot;Full SSL (Strict)&quot; doesn&#x27;t work with the certificate provided for free by Heroku:<p><pre><code>  By default Heroku offers a wildcard SSL certificate which only covers
  ‘*.herokuapp.com’. This means that ‘Full SSL’ can be utilized as a default,
  which does not require that the SAN contains your FQDN. To utilize
  Full (Strict) you will need to add your own SSL certificate to your
  Heroku app, which can be done by using their ‘SSL Endpoint’ add-on.
</code></pre>
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