Why is my agent’s Serper integration sending an empty HTTP body in n8n?

Below are some troubleshooting steps you can try when you face a 400 error with the HTTP Request node while using the Serper integration:

1. Double-check your query parameters and body
   A 400 error is often caused by incorrectly formatted parameters. If you’re passing arrays in your query or JSON data in your body, verify that they’re properly formed. For example, if your query contains an array, consider using the built-in “Array Format in Query Parameters” option and choose the correct format (No Brackets, Brackets Only, or Brackets with Indices).

2. Compare with your cURL request
   Since the same query works using cURL, inspect what differences exist between your cURL configuration and the HTTP Request node configuration. Look for discrepancies such as missing headers, different URL formatting, or differences in how parameters are encoded.

3. Validate your JSON (if applicable)
   If you’re sending JSON in the body, make sure it’s valid. You can run your JSON through a validator to catch any syntax issues. Also, if you’re using an expression to build the JSON, ensure that the result isn’t null or malformed. If you’re constructing JSON with expressions, make sure the entire JSON is wrapped with double curly brackets ({{ ... }}).

4. Review API documentation for Serper
   Although Serper works with cURL, sometimes an API expects data in a specific structure. Verify that the integration meets the API requirements as documented by Serper. Adjust your parameters as needed.

5. Enable additional logging or response details
   Within the HTTP Request node, enable options like “Include Response Headers and Status” to help provide more context on the error. This might give clues on whether the error is coming from a misformatted parameter, header, or some other request detail.

By carefully comparing the working cURL command to what n8n is sending, and ensuring all query parameters, headers, and body data are formatted correctly, you should be able to pinpoint the discrepancy causing the 400 error.