---
title: 1008: Invalid iMessage app message | API Docs
description: The imessage_app part failed validation — the message names the specific field.
---

The `imessage_app` message part is invalid. This is an HTTP 400 error. The `message` field names the specific problem, so read it before checking anything else.

## Troubleshooting

- `app.name` is required, and `app.team_id` must be 10 uppercase alphanumeric characters
- `app.bundle_id` is required and must not contain `:`
- `url` must be either an absolute `https://` URL or a `data:` URL
- `layout` must set at least one of `caption`, `subcaption`, `trailing_caption`, `trailing_subcaption`, or `image_url`
- `image_title` and `image_subtitle` require `image_url` — an overlay needs an image to sit on
- An `imessage_app` part must be the only part in the message

## Related

- [iMessage Apps](/guides/messaging/imessage-apps/index.md)
- [API reference: Send a message](/api/resources/chats/subresources/messages/methods/send/index.md)
- [Error Codes](/error/index.md)