@Kyle Wang It seems that you are facing an issue while sending a toast notification using Azure Notification Hubs. The error message "The Notification payload is invalid" indicates that the payload you are sending is not in the correct format.
To resolve this issue, you can try the following steps:
- Make sure that you are using the correct XML format for the toast notification. You can refer to the following link for the correct format: https://docs.microsoft.com/windows/uwp/design/shell/tiles-and-notifications/toast-xml-schema
- Check if you have provided the correct values for the required fields in the XML payload, such as the text for the toast message.
- Verify that the package identity and publisher identity in the Package.appxmanifest file match the values in the Azure portal.
- Ensure that the notification payload is less than 5KB in size.
If the issue persists, you can try sending a raw notification to see if it works. If it does, then the issue might be with the XML payload.