Slack Trigger (Events API) can’t verify Request URL: “Your request URL responded with an HTTP error / didn’t respond with challenge”

Questions
1

I’m trying to connect Slack with n8n Cloud using the Slack Trigger node (Trigger: “New Message Posted to Channel”).
OAuth access token works, Slack channels show in n8n, and the workflow is active.

But in Slack App → Event Subscriptions → Enable Events → Request URL, Slack verification fails.

Error message (exact)

  • “Your request URL responded with an HTTP error. Update your URL to receive a new request and challenge value.”

  • “Your URL didn’t respond with the value of the challenge parameter.”

What I tried

  • Using the n8n production webhook URL (workflow is active).

  • Re-connecting Slack credentials (connection test successful).

  • Confirmed the channel is visible/selectable in n8n Slack Trigger.

Request URL used in Slack

https://salman-akhter.app.n8n.cloud/webhook/[id]/webhook

Slack app details

  • Event Subscriptions: Enabled

  • Subscribed event: message posted to channel (I want to trigger on new messages)

  • OAuth scopes already added (example): channels:read, channels:history, chat:write, etc.

Please share your workflow

Workflow is simple:

image
image1908×1021 134 KB

2

Hi @SalmanAkhter035 , on the last screenshot the request url uses the test url (includes /webhook-test/db…) instead of the production webhook url. The test webhook url only works when you use workflow test execution until it is called once. You should publish your workflow and use the production webhook url as “Request URL” in your slack app.

Let me know if that fixes your issue.

3

Hey. did you manage to solve this issue?