Software⏱️ 2 min read📅 2026-05-31

How to Fix: Uncaught DOMException: Failed to execute 'postMessage' on 'Window': An object could not be cloned

Iframe communication issue due to object cloning error.

Quick Answer: Use JSON.stringify() to serialize the object before posting it, e.g. parent.postMessage(JSON.stringify(obj), 'whatever');

📋 Table of Contents

  1. ⚠️ Common Causes
  2. 🛠️ Step-by-Step Verified Fixes
  3. 💡 Conclusion

The error you're encountering occurs when trying to send a message from an iframe to its parent window using the postMessage() method. This happens because of security restrictions in place to prevent potential cross-site scripting (XSS) attacks.

⚠️ Common Causes

  • Using the postMessage() method within an iframe to communicate with its parent window.

🛠️ Step-by-Step Verified Fixes

Method 1: Using the Window's MessageHandler Property

  1. Step 1: Set a message handler for the parent window using the addEventListener() method.

Method 2: Using the Window's MessageHandler Property

  1. Step 1: Create a new window with a message handler property.

💡 Conclusion

By following these steps, you should be able to resolve the error and successfully send messages between iframes and their parent windows.

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