This warning is received when a promise in your application is rejected, but there's no `.catch()` handler in place to handle the rejection. This can lead to unhandled errors in your app, which is a bad practice as unhandled errors can crash your Node.js process. It is best to always handle promise rejections. Here's how you can add a `.catch()` to handle a rejected promise: ```javascript somePromiseFunction() .then(result => { // Operations to perform on successful promise resolution }) .catch(err => { // Operations to perform on promise rejection console.error(err); }); ``` This way if `somePromiseFunction()` rejects the promise, control goes to the `.catch()` block and performs whatever operation you've specified. If you have a situation where a lot of promises may reject and you can't catch them all, you can add a global handler using: ```javascript process.on('unhandledRejection', (reason, p) => { console.error('Unhandled Rejection at: Promise', p, 'reason:', reason); }); ``` This handler will catch any promise that gets rejected and isn't caught by a `.catch()` block. One final point to consider, it's better to always handle rejections where the promises are created so you can properly manage each individual error and keep your code robust and maintainable. The global handler should be a failsafe, not your primary means of error handling.