Troubleshooting 

No Slack message appears 

Check the following in order:

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

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 

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 

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 

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 

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 

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

Block Kit message rejected 

Check the JSON with Slack 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 

Issues can be reported at github.com/agencelex/typo3-notifications-slack/issues.