n8n HTTP Request node ERROR!!!
Hi everyone! 
I’m running into a problem while trying to trigger a Vapi outbound call using the HTTP Request node in n8n.
What I'm trying to do:
I want to use n8n to call Vapi’s API and trigger an outbound phone call to a user. Pretty straightforward automation.
What I’ve done so far:
Set up the n8n workflow using the HTTP Request node
Tested the Vapi API directly using the API Reference – it works perfectly there!
Copied the working JSON payload from Vapi into the n8n HTTP Request node without any changes
The problem:
When I hit “Execute Node” in n8n, I get the following error:
400 - {
"message": "Couldn't Get Assistant. Need Either
"error": "Bad Request",
"statusCode": 400
}
I’ve searched around and found that this usually means something's missing from the request body – but I’m confused because the exact same request works fine inside Vapi’s own API tester.
Anyone knows what might be going wrong when sending it from n8n?
Thanks a lot in advance
I’m running into a problem while trying to trigger a Vapi outbound call using the HTTP Request node in n8n. What I'm trying to do:I want to use n8n to call Vapi’s API and trigger an outbound phone call to a user. Pretty straightforward automation.
What I’ve done so far:Set up the n8n workflow using the HTTP Request node
Tested the Vapi API directly using the API Reference – it works perfectly there!
Copied the working JSON payload from Vapi into the n8n HTTP Request node without any changes
The problem:When I hit “Execute Node” in n8n, I get the following error:
400 - {
"message": "Couldn't Get Assistant. Need Either
assistant, assistantId, squad, Or squadId.","error": "Bad Request",
"statusCode": 400
}
I’ve searched around and found that this usually means something's missing from the request body – but I’m confused because the exact same request works fine inside Vapi’s own API tester.
Anyone knows what might be going wrong when sending it from n8n?
Thanks a lot in advance
