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

# Troubleshooting {#slack-troubleshooting}

## No Slack message appears {#no-slack-message-appears}

Check the following in order:

1.  `lex_notifications` and `notifications_slack` are installed.
1.  The notification's `via()` method includes `slack`.
1.  `routeNotificationForSlack()` returns a nonempty route, or an
    on-demand route is configured.
1.  The named webhook alias or Bot Token exists in TYPO3 configuration.
1.  TYPO3/PHP can reach the relevant Slack HTTPS host.
1.  An asynchronous Messenger worker is running if delivery is deferred.

## `Slack Bot Token is not configured` {#slack-bot-token-is-not-configured}

The notification uses an API route, but `botToken` is missing or empty.
Verify the environment variable supplied to `additional.php` and make
sure the CLI worker sees the same configuration as PHP-FPM.

## `Named Slack webhook is not configured` {#named-slack-webhook-is-not-configured}

A named webhook alias was selected, but no matching nonempty entry was
found under `webhooks`. Check spelling and configuration loading.

## `Invalid Slack Incoming Webhook URL` {#invalid-slack-incoming-webhook-url}

Direct/named webhooks must use HTTPS, approved Slack/GovSlack hosts and
a `/services/.../.../...` URL path, without custom ports or queries.

## `channel_not_found` or `not_in_channel` {#channel-not-found-or-not-in-channel}

Confirm that the Slack conversation ID is correct, that the app is
installed in the intended workspace and that the bot has access to the
conversation. Slack decides authorization; a syntactically valid ID is
not proof of permission.

## HTTP 429 / rate limits {#http-429-rate-limits}

Slack rate-limited the request. The exception may contain
`retryAfterSeconds`. Configure a Messenger retry strategy; it is not
applied automatically by this extension.

## HTTP 5xx / network errors {#http-5xx-network-errors}

Delivery may have occurred despite the error. Consider the potential
for duplicate Slack messages before retrying.

## Block Kit message rejected {#block-kit-message-rejected}

Check the JSON with [Slack Block Kit Builder](https://app.slack.com/block-kit-builder/).
The extension only validates top-level structure for raw JSON. Nested
block limits and requirements are ultimately enforced by Slack.

## Documentation and support {#documentation-and-support}

Issues can be reported at
[github.com/agencelex/typo3-notifications-slack/issues](https://github.com/agencelex/typo3-notifications-slack/issues).