datawhalechina/hello-agents · error

浏览器不支持流式响应，无法获取研究进度

Error message

浏览器不支持流式响应，无法获取研究进度

What it means

Thrown by the helloagents-deepresearch frontend when the /research/stream response succeeded (resp.ok) but response.body is undefined — i.e. this browser/runtime cannot expose the response as a ReadableStream. Since the whole deep-research UX depends on incrementally reading SSE frames, the code refuses to continue rather than hang on a request() that never yields chunks.

Source

Thrown at code/chapter14/helloagents-deepresearch/frontend/src/services/api.ts:42

    method: "POST",
    headers: {
      "Content-Type": "application/json",
      Accept: "text/event-stream"
    },
    body: JSON.stringify(payload),
    signal: options.signal
  });

  if (!response.ok) {
    const errorText = await response.text().catch(() => "");
    throw new Error(
      errorText || `研究请求失败，状态码：${response.status}`
    );
  }

  const body = response.body;
  if (!body) {
    throw new Error("浏览器不支持流式响应，无法获取研究进度");
  }

  const reader = body.getReader();
  const decoder = new TextDecoder("utf-8");
  let buffer = "";

  while (true) {
    const { value, done } = await reader.read();
    buffer += decoder.decode(value || new Uint8Array(), { stream: !done });

    let boundary = buffer.indexOf("\n\n");
    while (boundary !== -1) {
      const rawEvent = buffer.slice(0, boundary).trim();
      buffer = buffer.slice(boundary + 2);

      if (rawEvent.startsWith("data:")) {
        const dataPayload = rawEvent.slice(5).trim();
        if (dataPayload) {

View on GitHub (pinned to 606a07d341)

Solutions

1. Confirm the runtime: log `'body' in Response.prototype` or typeof resp.body — if undefined, the environment lacks streaming fetch.
2. Upgrade/switch to a modern browser (Chrome 76+, Firefox 69+, Safari 14.1+ for mature ReadableStream responses).
3. If a legacy runtime must be supported, implement a non-streaming fallback endpoint (POST /research and poll or wait for the full JSON result).
4. In tests, polyfill ReadableStream (e.g. web-streams-polyfill) or mock fetch with a body-providing stub.

export function supportsStreamingResponses(): boolean {
  return typeof ReadableStream !== 'undefined'
    && typeof Response !== 'undefined'
    && 'body' in Response.prototype;
}

if (!supportsStreamingResponses()) {
  useNonStreamingFallback(); // POST /research once, render final result
}

function hasReadableBody(resp: Response): resp is Response & { body: ReadableStream<Uint8Array> } {
  return resp.body != null && typeof (resp.body as ReadableStream).getReader === 'function';
}

if (!response.ok) { /* handled by error 25 path */ }
if (!hasReadableBody(response)) {
  renderStaticResult(await fetchFullResearch(payload));
}

When it happens

Trigger: resp.ok is true and resp.body is undefined/null: old browsers (fetch streams shipped ~2017+), some WebViews/inline browsers, certain polyfilled fetch implementations (e.g. older whatwg-fetch) that lack body, or test environments (jsdom) without stream support.

Common situations: Users on legacy Chrome/Safari or in-app browsers; corporate environments replacing fetch with a polyfill; running the UI in jsdom-based tests; service-worker fetch interception stripping the body in old sw-toolbox versions.

Related errors

• 研究请求失败，状态码：${response.status}
• stream request failed: ${resp.status} ${message}
• 智能体流式请求失败: ${resp.status}
• 研究请求失败，状态码：${response.status}
• msg

AI-assisted analysis of datawhalechina/hello-agents@606a07d341 (2026-08-14). Data as JSON: /api/errors/183271b0b09e1325. Report an issue: GitHub.