UnhandledPromiseRejectionWarning: Error: something went wrong

A Promise rejected and nothing caught the error.

Fix 1: Add .catch()

// ❌ No error handling
fetch('/api/data').then(res => res.json());

// ✅ Handle errors
fetch('/api/data')
  .then(res => res.json())
  .catch(err => console.error('Failed:', err));

Fix 2: Use try/catch with async/await

// ❌ No try/catch
async function getData() {
  const res = await fetch('/api/data');
  return res.json();
}

// ✅ Wrap in try/catch
async function getData() {
  try {
    const res = await fetch('/api/data');
    return await res.json();
  } catch (err) {
    console.error('Failed:', err);
  }
}

Fix 3: Global handler (for debugging)

process.on('unhandledRejection', (reason) => {
  console.error('Unhandled rejection:', reason);
});

Related resources

• JavaScript array methods cheat sheet
• JavaScript complete guide