Why are my push notifications with images failing to deliver, sometimes with a 'Message Too Big' error?

Push notification services, such as Apple's Push Notification Service (APNs) and Google's Firebase Cloud Messaging (FCM), have strict limits on the size of a notification's payload. If your notifications are failing, it is often because the payload size exceeds these limits.

A common cause for this issue is embedding large data directly into the push payload, such as including a full image encoded in Base64 format. This practice can easily make the payload too large, causing the push service to reject the notification and resulting in a delivery failure.

To resolve this, you should follow the best practice for sending rich media in push notifications:

1. Host the image externally. Upload your image to a server where it is accessible via a public URL.
2. Include the image URL in the payload. Instead of sending the image data itself, simply include the direct URL to the image in the appropriate field of your push notification settings.

By sending a lightweight URL instead of the heavy image data, you keep the payload size small, ensuring your notifications are delivered successfully.