title: Facebook - Curl Error SSL_CACERT SSL certificate
body: <p>I am getting "<strong>Curl Error : SSL_CACERT SSL certificate problem: unable to get local issuer certificate</strong>" when asking Facebook to <a href="https://developers.facebook.com/tools/debug/sharing/" rel="nofollow noreferrer">scrape my page</a> over https. How can I fix this so that Facebook can scrape my page without errors?</p>
  
  <p>The page is hosted via Apache 2.4 proxying to IIS 10. Apache handles all certificates and IIS is on the local network. My page is running asp code (so no php) and solutions similar to these: <a href="https://stackoverflow.com/questions/41019104/facebook-auth-curl-error-60-ssl-certificate">edit the php.ini file</a> or <a href="https://stackoverflow.com/questions/37869680/laravel-5-2-socialite-facebook-login-curl-error-60">adding curl.pem to php folder</a> will not work fix my problem ... or so I think?!? </p>
  
  <p>IIS has no certificate installed.</p>
  
  <p>I do have <code>extension=php_curl.dll</code> enabled -- and <code>extension_dir = 'C:\64bit\php-7.0.6-Win32-VC14-x64\ext'</code> defined in my php.ini file. I followed <a href="http://www.web-site-scripts.com/knowledge-base/article/AA-00480/0/Curl-installation-on-Windows-Apache-and-IIS.html" rel="nofollow noreferrer">these steps</a> to install Curl on Windows. And phpinfo.php confirms that cURL is enabled (cURL Information 7.47.1).</p>
  
  <p>My proxy setup in my Apache config file is:</p>
  
  <pre><code>&lt;IfModule mod_proxy.c&gt;
      ProxyRequests Off
      ProxyPass           / http://192.168.1.101:88/com_ssl/
      ProxyPassReverse    / http://192.168.1.101:88/com_ssl/
      RewriteRule ^(.+)$  https://www.domainname.com/$1 [P,L] 
  &lt;/IfModule&gt;
  </code></pre>
  
  <p>I have no <strong>RequestHeader</strong> defined in my Apache proxy config file, <a href="https://www.netnea.com/cms/apache-tutorial-9_setting-up-a-reverse-proxy/" rel="nofollow noreferrer">such as suggested here in Step 10</a>: </p>
  
  <pre><code>RequestHeader set "X-RP-UNIQUE-ID"     "%{UNIQUE_ID}e"
  RequestHeader set "X-RP-REMOTE-USER"     "%{REMOTE_USER}e"
  RequestHeader set "X-RP-SSL-PROTOCOL"     "%{SSL_PROTOCOL}s"
  RequestHeader set "X-RP-SSL-CIPHER"     "%{SSL_CIPHER}s"
  </code></pre>
  
  <p>Is this what is missing to fix the error?</p>