HTML messageerror DOM Event: Reference and Examples

When someone interacts with a webpage, the browser sends events to the relevant JavaScript code. The messageerror event happens when a message could not be deserialized by the receiver.

When messageerror happens

A message could not be deserialized by the receiver.

You can listen for it using addEventListener(). That keeps event handling separate from HTML attributes such as onclick and works well with modern code organization.

A small working example

<p>Messages require a sender such as another window or a MessagePort.</p>
<p id="event-status" role="status">Waiting for messageerror...</p>
<script>
    const eventTarget = window;
    const eventStatus = document.getElementById("event-status");

    if (eventTarget) {
        eventTarget.addEventListener("messageerror", (eventDetails) => {
            eventStatus.textContent = "messageerror event received";
            console.log(eventDetails.type, eventDetails.target);
        });
    }
</script>

Reading the code

The browser listens for messageerror on the relevant target. When the event occurs, the callback receives eventDetails, updates the status message and logs the event name and target in Developer Tools.

Requires a structured-clone failure in a message channel; ordinary postMessage sends do not always reproduce it.

Some events need a specific browser condition, another tab or window, or a Web Component to reproduce. Read the trigger steps carefully before deciding that an event handler is not working.

Try it in your browser

Open the page, show the Console panel, and follow this test: Requires a structured-clone failure in a message channel; ordinary postMessage sends do not always reproduce it. Then change one thing in the example and observe whether the event still fires.

Common Beginner Mistakes

• Expecting messageerror to fire without its required user action or browser condition.
• Requires a structured-clone failure in a message channel; ordinary postMessage sends do not always reproduce it.
• Adding repeated event listeners without considering cleanup or unwanted side effects.

Key Takeaways

• messageerror reports a message could not be deserialized by the receiver.
• addEventListener("messageerror", ...) listens for the event on the appropriate target.
• Requires a structured-clone failure in a message channel; ordinary postMessage sends do not always reproduce it.