How to give two response for one request in nodejs

(node:4148) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Cant set headers after they are sent.
(node:4148) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

{
fs.readFile('public/html/sucess.html', function (err, data) {
          res.write(data);
          res.end();
      });
webtrfy(downloadLink)
      .then(function (buffer) {
         console.log('creating the file');
         //-------------------------------------------
         res.setHeader('Content-Type', 'application/x-trt');
         res.setHeader('Content-Disposition', `inline; filename="${fileName}.trt"`);
         res.setHeader('Cache-Control', 'public, max-age=2592000'); // 30 days
         res.send(buffer);
         console.log(fileName +'.trt created');
         res.end();
         //-------------------------------------------
      });
}