Express Js API Http到Https不起作用

我尝试从我的域的HTTP到HTTPS，但是遇到错误。

我使用在8081端口上运行的express.js 4编写了API。我的前端在80 Nginx端口上运行。SSL证书提供者是Amazon，我正在使用负载平衡器，并成功与https一起运行。

我必须使用HTTPS运行我的API，但出现以下错误

_tls_common.js:85
      c.context.setKey(options.key, options.passphrase);
                ^
Error: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
    at Object.createSecureContext (_tls_common.js:85:17)
    at Server (_tls_wrap.js:776:25)
    at new Server (https.js:27:14)
    at Object.createServer (https.js:48:10)
    at Object.<anonymous> (/ubuntu/server.js:95:25)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_node.js:427:7)
    at startup (bootstrap_node.js:151:9)
    at bootstrap_node.js:542:3

我的节点js代码：

var http = require('http');
var https = require('https');

var options = {
   key: fs.readFileSync('/etc/ssl/certs/cert.pem',{passphrase: 'XXXXX'}),
   cert: fs.readFileSync('/etc/ssl/certs/ca-certificates.crt'),

 };

var httpServer = http.createServer(app);
var httpsServer = https.createServer(options, app);

httpServer.listen(8081);

httpsServer.listen(8081);