Webhook test/delivery is failing

What you may be seeing

• A webhook test or real event has a failed delivery status, or the receiver rejects the signature.

What usually causes it

• Endpoint is not reachable public HTTPS or resolves to a private/local target.
• Receiver computes HMAC over parsed/re-serialized JSON instead of the exact raw body.
• Receiver takes longer than the delivery timeout or returns non-2xx.
• The signing secret was lost; it is only shown at creation.

Do this

1. Use Settings → Developer → Webhooks and run the endpoint's test/ping.
2. Confirm the URL is public HTTPS and your server returns any 2xx within 10 seconds.
3. Verify X-CanvasRelay-Signature by HMAC-SHA256 over the exact raw request body using the endpoint's whsec_ secret.
4. Make the receiver idempotent because failed deliveries retry on backoff.
5. If the secret was lost, create a replacement webhook endpoint configuration and store the new shown-once secret.

You know it is fixed when

• The dashboard's last delivery status succeeds and the receiver validates/processes both ping and subscribed real events.