AI Agent Not Passing JSON Data to HTTP Request in n8n

Questions
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1

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:hammer_and_wrench: Problem Description:
I am using the AI Agent in n8n to collect user input and send it to the HTTP Request node. However, when I map the output from the AI Agent to {{$fromAI('json')}}, the HTTP Request node fails with errors.

  • Sometimes the request receives an empty body (query: {}) instead of the expected JSON.
  • If I manually input data, the HTTP Request node works fine.
  • Authorization (Bearer Token) is properly set in the headers.
  • Tried using {{$json}} instead of $fromAI(‘json’), but still facing issues.
    Screenshot 2025-02-24 at 2.45.43 PM
    Screenshot 2025-02-24 at 2.45.43 PM2908×1428 185 KB

Describe the problem/error/question

What is the error message (if any)?

Please share your workflow

(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)

Share the output returned by the last node

Information on your n8n setup

  • n8n version:
  • Database (default: SQLite):
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via (Docker, npm, n8n cloud, desktop app):
  • Operating system:
2

It looks like your topic is missing some important information. Could you provide the following if applicable.

  • n8n version:
  • Database (default: SQLite):
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via (Docker, npm, n8n cloud, desktop app):
  • Operating system:
3

n8n veersion : 1.78.1
database : SQLlite
n8n executions_process : default
Running n8n : npm
Operating system. : linux

4

Hey @Bhojraj_pilaniya1,

I see that your AI Agent’s output is not properly mapping to the HTTP Request node , which sometimes causes an empty request body (query: {}) . Here’s how to fix it:

:white_check_mark: 1. Ensure the AI Agent Outputs Proper JSON

Modify the System Message in the AI Agent to force structured output:

When responding, always return valid JSON. Example format:
{
“query”: {
“key1”: “value1”,
“key2”: “value2”
}
}
Do not include extra text, explanations, or formatting outside this JSON structure.

•	Then test with:

Example input: “Generate a request for user details”

• The AI must return structured JSON, not plain text.

:white_check_mark: 2. Update the JSON Mapping in the HTTP Request Node

Instead of:

{{$fromAI(‘json’)}}

Use:

{{$json[“query”] || “{}”}}

• This ensures a fallback value ({}) if query is missing.

:white_check_mark: 3. Debug the AI Output Before the HTTP Request

• Add a Function node between the AI Agent and HTTP request.

• Inside the Function node, use:

return [{ “debug”: JSON.stringify($json) }];

• Run the workflow and check the debug output to confirm the AI sends valid JSON.

Try these fixes and let me know if the issue persists! :rocket: