InvokeHTTP returns empty or truncated content

Summary

InvokeHTTP may return an empty body or only part of the expected response. This usually results from response streaming, content length issues, or API behavior.

Symptom

• Response content is empty

• The viewer shows zero or very few bytes

• JSON is cut off mid-object

• Downstream processors fail due to malformed content

Root Cause

• The API returns no content for certain status codes

• The server uses chunked transfer encoding and closed early

• Max response size is exceeded

• InvokeHTTP is configured to ignore the response body

• Redirects are not followed

How to Fix It

Verify the API behavior

Check whether the endpoint actually returns a body for your status code.

Enable Follow Redirects

Many APIs return 301 or 302 with no body unless redirects are followed.

Set Always Output Response to true

Ensures a FlowFile is created even for empty responses.

Check Max Response Size

Increase the limit if large payloads are expected.

Inspect the Raw Response

Add LogAttribute or LogMessage to dump headers for debugging.

Prevention

• Confirm API behavior before building flows

• Use test calls with the API’s documentation examples

• Set reasonable max response size values