Probleme mit Google Calendar + Respond to Webhook in n8n

[Dilawar_Khan]

Subject / Title

Issue: Webhook → Google Calendar → Respond to Webhook (not working as expected)

Message

Hello Support,

I am trying to connect Vapi → n8n → Google Calendar.

The goal: Caller books appointment → Event is created in Google Calendar → n8n sends response back to Vapi via “Respond to Webhook”.

My setup

1. Webhook node (receiving data from Vapi)

2. Google Calendar node (Create Event)

3. Respond to Webhook node (send result back to Vapi)

Problems

1. Calendar sometimes creates the event, but the time is always wrong (all appointments go to 02:00).

2. If I try to fix with expressions, Google Calendar gives “Bad request – please check your parameters”.

3. Respond to Webhook does not always send the response back to Vapi – sometimes Vapi doesn’t get any confirmation.

My questions

1. What is the correct format for Start/End date in Google Calendar (RFC3339 example for n8n)?

2. How should I format the Respond to Webhook body so that Vapi accepts it? (Does it need { toolCallId, result } ?)

3. Do I need to add special headers (like Content-Type: application/json) in Respond to Webhook?

4. Do you have a working example of the flow: Webhook → Calendar Create Event → Respond to Webhook?

Thank you