Getting a Form Submission Error

Questions
1

I am stuck as when I submit a form, it is giving me an error (attached image). The feedback is supposed to go through the wait node (On Form Submit Option) but it is giving me this error.

image
image672×245 8.13 KB

Node Configuration:
{
“nodes”: [
{
“parameters”: {
“resume”: “form”,
“formTitle”: “LinkedIn Post Review”,
“formDescription”: “Review the post details in the email, then choose an action below. If you choose Regenerate, please describe what should change so the AI can revise it correctly (tone, data used, CTA, hashtags, image, etc.).”,
“formFields”: {
“values”: [
{
“fieldLabel”: “Action”,
“fieldType”: “dropdown”,
“fieldOptions”: {
“values”: [
{
“option”: “Approve”
},
{
“option”: “Regenerate”
},
{
“option”: “Reject”
}
]
},
“requiredField”: true
},
{
“fieldLabel”: “Feedback”,
“fieldType”: “textarea”,
“placeholder”: “Required if you selected Regenerate. Optional otherwise.”
}
]
},
“options”: {}
},
“name”: “Wait for Review”,
“type”: “n8n-nodes-base.wait”,
“typeVersion”: 1.1,
“position”: [
4160,
11328
],
“id”: “52fda474-a4fe-4574-ba76-9a683f22df7d”,
“webhookId”: “c6bb81bb-5081-4c0b-ab40-1ddd6576b58d”
}
],
“connections”: {
“Wait for Review”: {
“main”: [

]
}
},
“pinData”: {},
“meta”: {
“templateCredsSetupCompleted”: true,
“instanceId”: “9e6cac95a494feaa9ac6c3fef00efec59fbfc3f82d0cb2cf36b884f7738fa241”
}
}

2

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3

Hi @Deserve_MERCY

The “Problem submitting response” error in an n8n Wait node (Form resume) is almost always caused by a Webhook URL mismatch or a Network/Reverse Proxy configuration issue​.

When you use the “On Form Submit” option, n8n generates a unique webhook URL. If the n8n instance cannot “reach itself” via that URL, or if the URL being used by the browser doesn’t match the one the server expects, the submission fails.

If you are self-hosting (Docker/npm), n8n needs to know its own public address to generate the form link. If this is not set, it defaults to localhost, which works for you but fails when the form tries to “post” the data back to the server.

The Fix: Check your .env file or Docker Compose environment variables. Ensure WEBHOOK_URL is set to your full public domain (including https://).

# Example for Docker Compose
environment:
  - WEBHOOK_URL=https://n8n.yourdomain.com/

After changing this, you must restart the container and re-send the email/link to the reviewer, as the old link was generated with the wrong URL.

If WEBHOOK_URL is correct, the issue is likely that your reverse proxy (Nginx, Traefik, Caddy) is blocking the POST request or stripping headers.

Check these settings:

  1. SSL Termination: Ensure you are using HTTPS. n8n forms often fail on plain HTTP due to browser security policies.
  2. Payload Size: If the “Feedback” textarea is very long, ensure your proxy allows the request size (e.g., client_max_body_size 10M; in Nginx).
  3. CORS/Headers: Ensure your proxy is passing the Host header correctly.

If this is happening in a Production execution (the workflow is Active), but works in Manual testing:

  • The Cause: Manual executions use a /webhook-test/ path, while production uses /webhook/.
  • The Fix: Ensure you are not manually triggering the workflow and then trying to use a production link (or vice versa). If the workflow is “Active,” the link sent to the user must be the Production URL.

Does it help?

4

Hi @Deserve_MERCY Welcome!
Open the form page with the browser console on (F12), hit Submit, and read what fails. A CORS block on /form-waiting/.../n8n-execution-status from origin null means the form page’s own request back to n8n is being rejected, so the submission never lands and the page reports a form error.
The cause is the CSP sandbox header n8n puts on form pages, which omits allow-same-origin. If you’re self-hosted behind Nginx, override the header until it’s fixed upstream:

proxy_hide_header Content-Security-Policy;
add_header Content-Security-Policy "sandbox allow-downloads allow-forms allow-modals allow-popups allow-scripts allow-same-origin allow-top-navigation-by-user-activation";

Tracking issue:

5

More than likely this error has to do with the WEBHOOK_URL or “N8N_EDITOR_BASE_URL”. If you are self hosted behind a reverse proxy, tunnel, or Docker try to make sure those env vars match your actual public facing URL. The form’s resume URL is generated from this at execution time so a mismatch is most likely the cause of the error you are seeing.

Something else that might be worth checking here is whether your JSON shows `“connections”: {“Wait for Review”: {“main”: []}}` with no downstream connection. This shouldn’t cause a submit error but doing a double check that is intentional is probably a good idea.