---
title: "Error handling"
manual: "Laravel-style Notification System - Slack Channel"
version: "1.0"
permalink: "https://docs.typo3.org/permalink/agencelex/notifications-slack:slack-errors@1.0"
source: "Reference/ErrorHandling.rst"
rendered: "2026-10-16T12:40:55+00:00"
---

# Error handling {#slack-errors}

Delivery failure is reported by throwing an exception, rather than
quietly marking a failed message as successfully delivered.

## `SlackTransportException` {#slacktransportexception}

The exception defines these readonly properties:

| Property | Type | Meaning |
| --- | --- | --- |
| `httpStatus` | `?int` | HTTP status if a response was received. |
| `retryAfterSeconds` | `?int` | Parsed Slack Retry-After header, when available. |
| `retryable` | `bool` | Whether retrying might be appropriate. |

## Transport behavior {#transport-behavior}

| Case | Outcome |
| --- | --- |
| Webhook HTTP 2xx + `ok` | Success, returns `['ok' => true]`. |
| API HTTP 2xx + JSON `ok: true` | Success, returns the decoded Slack response. |
| HTTP 429 | Exception; retryable; parses `Retry-After`. |
| HTTP 5xx | Exception; retryable; delivery may have occurred. |
| Other non-2xx responses | Exception; generally non-retryable. |
| Request-level network exception | Exception; retryable; delivery state unknown. |
| API JSON `ok: false` | Exception with a sanitized Slack error code; selected errors retryable. |
| Unexpected/malformed response | Exception; not considered successful. |

Network errors are intentionally not chained into public exceptions;
some HTTP client exception strings can contain a webhook URL, which is
itself a secret.

## Catching failures in application code {#catching-failures-in-application-code}

```php
use Lex\Notifications\Slack\Exception\SlackTransportException;

try {
    $manager->route('slack', 'webhook:monitoring')
        ->notify(new DeploymentCompleted());
} catch (SlackTransportException $exception) {
    // Log a safe operational category; never log webhook URLs or tokens.
    $retryable = $exception->retryable;
    $retryAfter = $exception->retryAfterSeconds;
}
```

For deferred delivery, let the Messenger/core notification worker handle
exceptions according to its configured failure and retry policy. Reading
`retryAfterSeconds` does not itself schedule a retry. A failed send
may have reached Slack before a network error was observed.