Discord bot UnhandledPromiseRejectionWarning in production ( HEROKU) [duplicate] - node.js

Question

This question already has answers here:
Why am I getting a ReferenceError: AbortController is not defined in Discord.js v13?
(3 answers)
Closed 1 year ago.
I deployed my discord bot to Heroku but It is giving an error of unhandled promise rejection
Here are the logs
2021-09-10T20:50:26.000000+00:00 app[api]: Build started by user codertanishq#gmail.com
2021-09-10T20:50:45.558185+00:00 app[api]: Deploy c608c194 by user codertanishq#gmail.com
2021-09-10T20:50:45.558185+00:00 app[api]: Release v11 created by user codertanishq#gmail.com
2021-09-10T20:50:46.000000+00:00 app[api]: Build succeeded
2021-09-10T20:50:46.978335+00:00 heroku[web.1]: State changed from crashed to starting
2021-09-10T20:50:48.877754+00:00 heroku[web.1]: Starting process with command `npm start`
2021-09-10T20:50:51.529490+00:00 app[web.1]:
2021-09-10T20:50:51.529505+00:00 app[web.1]: > start#1.0.0 start /app
2021-09-10T20:50:51.529506+00:00 app[web.1]: > node ./src/bot.js
2021-09-10T20:50:51.529506+00:00 app[web.1]:
2021-09-10T20:50:51.762757+00:00 app[web.1]: (node:22) UnhandledPromiseRejectionWarning: ReferenceError: AbortController is not defined
2021-09-10T20:50:51.762758+00:00 app[web.1]: at RequestHandler.execute (/app/node_modules/discord.js/src/rest/RequestHandler.js:172:15)
2021-09-10T20:50:51.762758+00:00 app[web.1]: at RequestHandler.execute (/app/node_modules/discord.js/src/rest/RequestHandler.js:176:19)
2021-09-10T20:50:51.762758+00:00 app[web.1]: at RequestHandler.push (/app/node_modules/discord.js/src/rest/RequestHandler.js:50:25)
2021-09-10T20:50:51.762759+00:00 app[web.1]: at async WebSocketManager.connect (/app/node_modules/discord.js/src/client/websocket/WebSocketManager.js:128:9)
2021-09-10T20:50:51.762759+00:00 app[web.1]: at async Client.login (/app/node_modules/discord.js/src/client/Client.js:245:7)
2021-09-10T20:50:51.762759+00:00 app[web.1]: (Use `node --trace-warnings ...` to show where the warning was created)
2021-09-10T20:50:51.763064+00:00 app[web.1]: (node:22) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
2021-09-10T20:50:51.763091+00:00 app[web.1]: (node:22) [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.
2021-09-10T20:50:51.847328+00:00 heroku[web.1]: Process exited with status 0
2021-09-10T20:50:51.902780+00:00 heroku[web.1]: State changed from starting to crashed

Answer 1

You would have to upgrade your node version. You may add the following to your package.json:
"engines": {
"node": "16.9.1",
}
And redeploy your project and it would work

Answer 2

Discord.js v13 needs AbortController to function, but it was only introduced in node versions 16 and above. You have two options to fix this error:
Upgrade your node version on heroku to 16 or above
Use a polyfill for your AbortController , AbortController-polyfill is a package to do that, you may utilise it like so:
const { AbortController } = require('abortcontroller-polyfill/dist/cjs-ponyfill');
global.AbortController = AbortController;