5 Common Async/Await Error‑Handling Pitfalls and How to Avoid Them

async/await makes JavaScript asynchronous programming more intuitive and elegant. However, when handling errors, this syntactic sugar also hides many pitfalls that are easy to overlook. As a developer who has experienced countless late‑night emergency fixes, I share five async/await error‑handling pitfalls I’ve encountered in production and how to avoid them.

Pitfall One: Forgetting to use try/catch to capture errors

The most common and basic mistake is completely forgetting to handle exceptions that may occur in asynchronous operations.

async function fetchUserData(userId) {
  const response = await fetch(`/api/users/${userId}`);
  const userData = await response.json(); // If the response is not valid JSON, an error is thrown
  return userData;
}

This code will throw an uncaught exception when the network fails, the server returns an error, or the JSON is invalid, potentially crashing the whole application.

Correct approach:

async function fetchUserData(userId) {
  try {
    const response = await fetch(`/api/users/${userId}`);
    const userData = await response.json();
    return userData;
  } catch (error) {
    console.error(`Failed to fetch user data: ${error.message}`);
    // Return a default value or re‑throw the error
    throw new Error(`Failed to fetch data for user ${userId}: ${error.message}`);
  }
}

Pitfall Two: Losing errors in a Promise chain

When mixing async/await with .then()/.catch() chain calls, error handling becomes confusing.

async function processData() {
  const rawData = await fetchData();
  // Error: the following error will not be caught by the current function's try/catch
  processResult(rawData).then(result => {
    // use result...
  });
}

Correct approach:

async function processData() {
  try {
    const rawData = await fetchData();
    // Method 1: add error handling in the chain
    processResult(rawData)
      .then(result => {
        // use result...
      })
      .catch(error => {
        console.error("Error processing result:", error);
      });
    // Method 2 (better): use await completely
    const result = await processResult(rawData);
    // use result...
  } catch (error) {
    console.error("Failed to process data:", error);
  }
}

Pitfall Three: Improper error handling inside loops

Error handling is especially complex when using async/await inside loops.

An error in one iteration can abort the whole processing flow, which may not be what you want.

Correct approach:

Or use Promise.allSettled to handle parallel operations:

Pitfall Four: Not handling synchronous errors inside async functions

A common misconception is that try/catch only catches errors from await expressions, ignoring that synchronous code can also throw errors.

Correct approach:

Pitfall Five: Not considering the Promise state returned by await

An await expression may resolve to a Promise whose value indicates an error state.

Correct approach:

async function fetchResource() {
  try {
    const response = await fetch('/api/resource');
    if (!response.ok) {
      throw new Error(`API error: ${response.status} ${response.statusText}`);
    }
    const data = await response.json();
    return data;
  } catch (error) {
    console.error("Failed to fetch resource:", error);
    throw error;
  }
}

Contributions are welcome.