Console: Uncaught (in promise) Error / TypeError / DOMException — unhandled promise rejection

Meaning

The text after "Uncaught (in promise)" is the real error — often a failed fetch, a TypeError, or code that threw inside an async function. Add error handling at the call site, return the promise so callers can catch, and use the unhandledrejection event to log missed ones.

Common causes

• fetch or other async call without .catch / try…catch
• Error thrown inside an async function that nobody awaits
• Rejected promise created by Promise.reject and ignored
• Extension or third-party script rejecting
• Missing await so the rejection escapes the surrounding try/catch

Detailed fix by platform

Code examples

async function load() {
  const res = await fetch('/api/data');
  if (!res.ok) throw new Error('HTTP ' + res.status);
  return res.json();
}

// Not handled: load();          -> Uncaught (in promise) Error: HTTP 500
load().catch(err => console.error('load failed', err));   // handled

How to diagnose

1. Message — What follows "Uncaught (in promise)"?
2. Stack — Which async call created it?
3. Await — Any missing await or catch?

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