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Help Needed: User Input Custom Field Not Sending Data to Webhook

  • March 9, 2026
  • 3 comments
  • 34 views
KOTO

Hi everyone,

I’m trying to send user messages from ManyChat to an n8n webhook. I created a Custom User Field called UserInput to store the last user message and set up an External Request step with the following JSON body:

 

{
"userinput": "{{UserInput}}",
"contactid": "{{user_id}}"
}

The contactid works fine, but the userinput field is always empty in n8n.

Here’s what I’ve checked so far:

  • The Custom User Field is of type Text.

  • I’m triggering the External Request after the user sends a message.

  • The webhook URL is correct and active in n8n.

The response I get from ManyChat is:

 

404 Not Found
{"code":404,"message":"The requested webhook \"POST Many-Chat\" is not registered.","hint":"The workflow must be active for a production URL to run successfully. Unlike test URL calls, production URL calls aren't shown on the canvas."}

It seems like either the user input isn’t being captured correctly, or the webhook call isn’t sending the field properly.

Has anyone encountered this issue before? How can I make sure the user’s last message is captured and sent correctly to my webhook?

Thanks in advance for your help!

    3 replies

    Gustavo Boregio
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    • Gustavo Boregio
    • Community Moderator & Expert
    • March 9, 2026

    Hey ​@KOTO it seems your N8N automation isn't active…?

    Does the -test webhook to N8N work correctly? If so, is your automation properly published?

    This looks like an N8N problem, not a Manychat problem.

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    Meaghan1
    • Meaghan1
    • Up-and-Comer
    • March 10, 2026

    Hey KOTO,

    I’ve run into similar issues before with ManyChat Custom User Fields not sending data properly. One thing to double-check is that the External Request step is triggered after the user input is fully saved, not immediately when the message is received. Sometimes adding a small “Wait” step (even 1 second) before the webhook can help ensure the field is populated.

    Also, make sure your workflow in n8n is active and not just in draft mode, because inactive workflows will return that exact 404 error.

    If you want, I found a helpful guide on this topic that explains step-by-step how to troubleshoot ManyChat to webhook connections, might save you some trial and error.

    Hope that helps!

    Devtrest
    • Devtrest
    • Up-and-Comer
    • March 11, 2026

    It looks like you actually have 2 separate issues here.

    First, the 404 error is from n8n, not from the custom field itself. That message usually means the webhook workflow is not active, or you’re using the wrong webhook URL. So I’d fix that part first, because if the webhook isn’t live, it won’t matter what Manychat sends.

    Second, for the empty UserInput field, the most common cause is that the custom field is not being saved before the External Request runs.

    I’d check these:

    • make sure the User Input step is saving the reply into UserInput

    • make sure the External Request happens after that step

    • try using the field picker again instead of typing the variable manually

    • test by sending the value back to yourself in a message first, just to confirm the field actually contains the text

    So in short:

    • fix the n8n webhook activation/URL first

    • then confirm the Manychat User Input step is really saving into the custom field before the request fires

    Most likely the webhook problem and the empty field are connected, but the first thing that stands out is that your n8n webhook is not active/registered.

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