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Kenil Vasani
Kenil Vasani

Kenil Vasani

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Asked: 2020-12-19T21:56:41+00:00

How to find which promises are unhandled in Node.js UnhandledPromiseRejectionWarning?

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Node.js from version 7 has async/await syntactic sugar for handling promises and now in my code the following warning comes up quite often: 

(node:11057) UnhandledPromiseRejectionWarning: Unhandled promise 
rejection (rejection id: 1): ReferenceError: Error: Can't set headers 
after they are sent.
(node:11057) 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.

Unfortunately there’s no reference to the line where the catch is missing.
Is there any way to find it without checking every try/catch block?

async-awaitnode.jspromiseunhandled-exceptionwarnings
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    1. Kenil Vasani

      Kenil Vasani

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      Best Answer

      listen unhandledRejection event of process.

      process.on('unhandledRejection', (reason, p) => {
  console.log('Unhandled Rejection at: Promise', p, 'reason:', reason);
  // application specific logging, throwing an error, or other logic here
});
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