---
title: 4001: Delivery failed | API Docs
description: Message could not be delivered.
---

Message could not be delivered. This may be due to an unreachable phone, service disruption, or exhausted retry attempts. This is an HTTP 500 error.

## Troubleshooting

- Try sending the message again
- If the problem persists, contact support with the `trace_id` from the error response

## Related

- [Sending messages](/guides/messaging/sending-messages/index.md)
- [Debugging](/guides/platform/debugging/index.md)