title: "RequestError: Error: unable to verify the first certificate" error after updating certificate of API server
body: <p>I have this website (let's call it a.com) which is on AWS. It is done using NodeJs backend and view front end. It is calling another system API (let's call it b.com) for the DATA from some other URL.</p>
  
  <p>This site was working fine. We updated SSL certificate of site b.com and now site a.com is not able to receive data from site b.com.</p>
  
  <p>When I checked the error log on AWS, this is the error I found:</p>
  
  <pre><code>RequestError: Error: unable to verify the first certificate
  at new RequestError (/var/app/current/node_modules/request-promise-core/lib/errors.js:14:15)
  at Request.plumbing.callback (/var/app/current/node_modules/request-promise-core/lib/plumbing.js:87:29)
  at Request.RP$callback [as _callback] (/var/app/current/node_modules/request-promise-core/lib/plumbing.js:46:31)
  at self.callback (/var/app/current/node_modules/request/request.js:185:22)
  at emitOne (events.js:116:13)
  </code></pre>
  
  <p>What can be the issue?</p>
  
  <p>Can I do any settings on my NodeJs server to load data from b.com?</p>
  
  <p>The site is working fine on my localhost.</p>