How to fix TypeError: asyncFunction is not a function (async function call failed) in Node.js

Node.jsBEGINNERMEDIUMUpdated Dec 22, 2025· 160 views

This error occurs when JavaScript tries to call an async function that hasn't been properly defined or declared. Most commonly, it's caused by missing semicolons between statements, where the parser misinterprets code structure.

Quick fix

Fixes TypeError: asyncFunction is not a function (async function call failed)

// ❌ WRONG - Missing semicolon
const fs = require('fs')
(async () => {
  console.log('This causes an error');
})();

// ✅ CORRECT - Add semicolon
const fs = require('fs');
(async () => {
  console.log('This works fine');
})();
  1. Check for missing semicolons after statements
  2. Verify the function is properly defined
  3. Check for import/export issues
  4. Verify you're calling a function, not a property
node.js — error
// ❌ WRONG - Missing semicolon
const fs = require('fs')
(async () => {
  console.log('This causes an error');
})();
// ✅ CORRECT - Add semicolon
const fs = require('fs');
(async () => {
  console.log('This works fine');
})();
TypeError: asyncFunction is not a function (async function call failed)

What this error means

This TypeError indicates that you attempted to invoke something as a function, but the value is not actually a function. In the context of async functions, this typically happens when: 1. A function declaration or assignment is incomplete or malformed 2. Missing semicolons cause the parser to misinterpret your code (automatic semicolon insertion failure) 3. The variable name doesn't reference a valid function 4. An async function expression wasn't properly assigned or defined JavaScript's parser becomes confused about where statements begin and end, treating unrelated statements as function calls.

Typical symptoms

  • TypeError appears when you try to use an async function
  • Error happens immediately when the script runs, not during execution
  • Code works fine with different formatting or after adding semicolons
  • The error mentions a specific variable name that should be a function

Common causes

  1. Missing semicolon after a require() or const statement, followed by a line starting with parentheses
  2. Typo or misspelling in the function name
  3. Trying to call a property that isn't a function (e.g., calling a string or number)
  4. Function declaration syntax error or incomplete assignment
  5. Module import/export mismatch - function isn't exported or imported correctly
  6. Scope issue - async function defined in a different scope than where it's called

How to fix "TypeError: asyncFunction is not a function (async function call failed)"

1Check for missing semicolons after statements

The most common cause is missing a semicolon after require() or variable declarations. When the next line starts with parentheses, JavaScript misinterprets the code:

javascript
// ❌ WRONG - Missing semicolon
const fs = require('fs')
(async () => {
  console.log('This causes an error');
})();

// ✅ CORRECT - Add semicolon
const fs = require('fs');
(async () => {
  console.log('This works fine');
})();

Alternatively, place a semicolon before the parentheses:

javascript
const fs = require('fs')
;(async () => {
  console.log('This also works');
})();
2Verify the function is properly defined

Make sure the async function is declared correctly and the variable name is spelled consistently:

javascript
// ❌ WRONG - Function not assigned
const asyncFunction {
  return 'invalid';
};

// ✅ CORRECT - Proper async function declaration
const asyncFunction = async () => {
  return 'valid';
};

// ✅ CORRECT - Async function declaration
async function asyncFunction() {
  return 'valid';
}
3Check for import/export issues

If you're using ES6 modules, ensure the async function is properly exported and imported:

javascript
// In module.js
// ❌ WRONG - Forgot export
const asyncFunction = async () => {
  return 'data';
};

// ✅ CORRECT - Export the function
export const asyncFunction = async () => {
  return 'data';
};

// In main.js
// ✅ Import correctly
import { asyncFunction } from './module.js';
await asyncFunction();
4Verify you're calling a function, not a property

Make sure you're not accidentally treating a non-function value as a function:

javascript
// ❌ WRONG - asyncFunction is a property, not a method
const obj = {
  asyncFunction: 'just a string'
};
await obj.asyncFunction(); // TypeError

// ✅ CORRECT - asyncFunction is an actual function
const obj = {
  asyncFunction: async () => {
    return 'data';
  }
};
await obj.asyncFunction(); // Works
5Use top-level await for IIFE patterns

Instead of immediately-invoked async function expressions (IIFE), consider using top-level await in Node.js 14.8+:

javascript
// ❌ OLD - IIFE pattern (error-prone)
(async () => {
  const data = await fetch('https://api.example.com');
  console.log(data);
})();

// ✅ NEW - Top-level await (cleaner, requires "type": "module" in package.json)
const data = await fetch('https://api.example.com');
console.log(data);

Make sure your package.json has "type": "module" for ES modules.

Advanced notes

Automatic Semicolon Insertion (ASI): JavaScript's ASI rules don't always insert semicolons where you expect. A line starting with [, (, or a few other characters won't trigger ASI from the previous line. This is why explicit semicolons are safer.

CommonJS vs ES Modules: If you're mixing CommonJS (require) and ES modules (import), ensure consistency. The error often occurs when the transition isn't clean.

Async/Await Scope: Remember that await can only be used inside an async function or at the top level of a module (in Node.js 14.8+). Attempting to use await in a non-async context will cause related errors.

Linting: Use ESLint with rules like semi (enforce semicolons) and no-unused-expressions to catch these issues during development.

Frequently asked questions

What does "TypeError: asyncFunction is not a function (async function call failed" mean?
This TypeError indicates that you attempted to invoke something as a function, but the value is not actually a function. In the context of async functions, this typically happens when: 1. A function declaration or assignment is incomplete or malformed 2.
How do I fix "TypeError: asyncFunction is not a function (async function call failed"?
This error occurs when JavaScript tries to call an async function that hasn't been properly defined or declared. Most commonly, it's caused by missing semicolons between statements, where the parser misinterprets code structure.
What causes "TypeError: asyncFunction is not a function (async function call failed"?
Missing semicolon after a require() or const statement, followed by a line starting with parentheses Typo or misspelling in the function name Trying to call a property that isn't a function (e.g., calling a string or number)
Is the "TypeError: asyncFunction is not a function (async function call failed" error serious?
It is a medium-severity error — more of a blocker than a risk. The steps above resolve it.

Official resources & further reading