OtterMind/Chat2DB · error · TypeError

The response body is empty.

Error message

The response body is empty.

What it means

sseFetch throws a TypeError when the response has no body (response.body is null/undefined). This check runs after the status-ok check, so the server returned a successful status but with an empty body — which is invalid for an SSE stream that must contain event data. The body stream is required for the downstream sseStream parser to iterate over chunks.

Solutions

1. Verify the backend SSE endpoint actually writes data to the response body.
2. Check proxy configuration (disable buffering: proxy_buffering off; X-Accel-Buffering: no).
3. Handle this specific error in the catch and show 'AI returned no response' to the user.
4. Confirm the Content-Type header is text/event-stream and the endpoint is not being intercepted by a caching layer.

Example fix

// before
const response = await sseFetch(baseURL, requestInit);

// after
try {
  const response = await sseFetch(baseURL, requestInit);
  // ... process response.body
} catch (e) {
  if (e instanceof TypeError && /body is empty/i.test(e.message)) {
    onError('AI service returned an empty response. Check backend SSE configuration.');
    return;
  }
  throw e;
}

function isEmptyBodyError(e: unknown): e is TypeError {
  return e instanceof TypeError && /body is empty/i.test(e.message);
}

try {
  const response = await sseFetch(baseURL, requestInit);
} catch (e) {
  if (isEmptyBodyError(e)) {
    onError('AI service returned no data. Check SSE/streaming backend configuration.');
    return;
  }
  throw e;
}

When it happens

Trigger: The AI endpoint returns HTTP 200 with an empty body (Content-Length: 0). A misconfigured proxy strips the body. A streaming endpoint sends headers but closes the connection before any data. A redirect that resolves to an empty response.

Common situations: Reverse proxy (nginx/cloudflare) buffering configuration drops the stream body. Backend middleware that consumes or discards the body before the SSE handler writes. Network interruption after headers but before body data.

Related errors

• Fetch failed with status
• The response content-type
• The baseURL is not valid!
• The baseURL is not valid!
• Missing file

AI-assisted analysis of OtterMind/Chat2DB@5ee1e990e7 (2026-08-14). Data as JSON: /api/errors/999d77416c38dc0b. Report an issue: GitHub.

Appendix: source

Thrown at chat2db-community-client/src/components/SSERequest/sseFetch.ts:60

  /** ---------------------- response middleware ---------------------- */
  if (typeof middlewares.onResponse === 'function') {
    const modifiedResponse = await middlewares.onResponse(response);

    if (!(modifiedResponse instanceof Response)) {
      throw new TypeError('The options.onResponse must return a Response instance!');
    }

    response = modifiedResponse;
  }

  /** ---------------------- response check ---------------------- */
  if (!response.ok) {
    throw new TypeError(`Fetch failed with status ${response.status}`);
  }

  if (!response.body) {
    throw new TypeError('The response body is empty.');
  }

  /** ---------------------- return ---------------------- */
  return response;
};

export default SSEFetch;

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