Error 11200 : unable to fetch response URL between n8n & Twilio

Hi,

Before starting i should say that i am quite new and making this AI agent for the first time related to travel information . My AI agent is fetching all the required data from google sheet for sending the same through whatsapp chat.

My work flow is success when i execute the flow manually but it is not getting automatically triggered. I have contacted both n8n and Twilio,

Twilio has identified the issue: they’re getting “Error 11200 - unable to fetch response from URL” when trying to call my webhook, even though manual curl requests work fine.

Twilio’s Diagnosis:

This indicates a connectivity issue between Twilio’s servers and n8n cloud, specifically:

  1. SSL certificate issues (invalid or self-signed certificate)

  2. Firewall blocking Twilio’s IP ranges

  3. Access restrictions on the n8n cloud instance

  4. Response timeouts beyond 15 seconds

I need help in this urgently, i am stuck with this and need to fix this urgently.

Regards

Sunny

what I’ve tested so far, this usually comes down to

Making sure the webhook is in Production mode (not the test URL).

  • Confirming the webhook endpoint responds within 15 seconds otherwise Twilio times out even if the workflow keeps running.

  • Checking that the webhook URL is using a valid public SSL cert (no custom/self-signed certs

  • Verifying there are no IP restrictions or security settings blocking Twilio traffic on the n8n instance.

Thnx for your message. I have been trying to get the help from n8n but even for the paid account they are not been doing any help. Can you tell me how can i check the following at my end as suggeted by you.

  • Checking that the webhook URL is using a valid public SSL cert (no custom/self-signed certs

  • Verifying there are no IP restrictions or security settings blocking Twilio traffic on the n8n instance.

I am really sorry for being ignorant in all this and appreciate your kind help. My project is stuck only because of this.

Regards

Sunny