Webhook execution error: Hook executed successfully but returned HTTP 400 missing_text_or_fallback_or_attachments

Question

I am trying to integrate Slack with GitLab.

• I installed a webhook in slack and copied the webhook url to GitLab's app integration.
• I have also enabled the Slack integration in GitLab's integration setting.

However I keep getting the error:

Hook executed successfully but returned HTTP 400 missing_text_or_fallback_or_attachments

How can I avoid this error?

Answer 1

This is currently followed by gitlab-org/gitlab-foss issue 41853

It includes:

Don't use the Integration part.. read further.

Use Slack Notifications what's in the end of Project services if you scroll down on the Project > Settings > Integration page.

But even that does not seem to be always enough (it appears to work in the OP's case).
Check if you see any stack trace in sudo gitlab-ctl tail.