<!--
{
  "availability" : [
    "iOS: 18.4.0 -",
    "iPadOS: 18.4.0 -",
    "macCatalyst: 18.4.0 -",
    "macOS: 15.4.0 -",
    "visionOS: 2.4.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "WebKit",
  "identifier" : "/documentation/WebKit/WKWebExtension/MessagePort/Error/Code/messageInvalid",
  "metadataVersion" : "0.1.0",
  "role" : "Case",
  "symbol" : {
    "kind" : "Case",
    "modules" : [
      "WebKit"
    ],
    "preciseIdentifier" : "c:@E@WKWebExtensionMessagePortError@WKWebExtensionMessagePortErrorMessageInvalid"
  },
  "title" : "WKWebExtension.MessagePort.Error.Code.messageInvalid"
}
-->

# WKWebExtension.MessagePort.Error.Code.messageInvalid

Indicates that the message is invalid.

```
case messageInvalid
```

## Discussion

The message must be an object that is JSON-serializable.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)