Hello, I'm facing very weird issue, I have built a usuall tool in n8n - to check availability and book appointment. It has been done the same way as currently working solutions. Unfortunately I keep getting error: "Your server rejected

tool-calls

webhook. Error: " The production URL from n8n is correctly put in the tool configuration panel, the scenario is active. I have tried to duplicate scenarios in n8n, tried to duplicate the assistant, duplicate the tool and it all failed - while some other assistant who have the same type of n8n scenario as a tool (different webhook ofc) works as usual. Could you please help me? https://cdn.discordapp.com/attachments/1417112535471099925/1417112536591110214/Screenshot_2568-09-15_at_18.37.24.png?ex=68c94c65&is=68c7fae5&hm=83898debf4e751bc70f56fcfd19e8be392fe84175df36c68cb4bdca05f6de1b3&

Thanks for sharing all those details and screenshots! I couldn't find enough info to solve this one right away, so I'm escalating your issue to a human teammate who can dig in further. Just in case it's helpful while you wait: double-check that your webhook endpoint is accessible and that authentication (like secret tokens or custom headers) is set up as expected. You can find more about webhook/server message setup and troubleshooting in the [Vapi docs here](https://docs.vapi.ai/api-reference/webhooks/server-message?explorer=true) and [server authentication guide](https://docs.vapi.ai/server-url/server-authentication). Hang tight—someone will get back to you soon!

Hi! I can help you troubleshoot this webhook issue. The error usually points to the server rejecting the incoming request, which can be due to URL misconfigurations, authentication, or security rules. To pinpoint the cause, could you share if your webhook requires any API keys or custom headers, and whether your server logs show incoming requests from Vaio-Calendar? @Marcello

Hello @Lordvickthor, no the webhook doesn't require none of that. I'm starting the scenario in n8n with webhook, I'm putting the webhook url correctly in the configured tool, as in any other assistant that has similarly confiugured tool with different prod url, and this one does not work

That's good

Hi Marcello, To set up local webhook testing with Vapi, you'll need to use the

vapi listen

command along with a tunneling service like ngrok. Here's a quick guide to get you started: 1. **Start your local server**: Ensure your application server (e.g., a Node.js server) is running on a specific port, such as

localhost:3000

. 2. **Set up a tunnel**: Open a terminal and use ngrok to create a tunnel to your local machine.

ngrok http 4242

This creates a public URL that forwards to your local server. 3. **Start the webhook listener**: In a separate terminal, start the Vapi listener.

vapi listen --forward-to localhost:3000/webhook

This listens on port 4242 and forwards requests to your local webhook handler. 4. **Update webhook URLs**: Go to your Vapi Dashboard and set your webhook URLs to the ngrok URL. 5. **Test your webhooks**: Trigger webhook events and see them in your terminal for real-time debugging. For more details, you can refer to the [Local webhook testing guide](https://docs.vapi.ai/cli/webhook).