Mintplex-Labs/anything-llm · critical · Error

No webSocketDebuggerUrl — is Chromium running?

Error message

No webSocketDebuggerUrl — is Chromium running?

What it means

Thrown by cdp-input.js (the click/type/key injection utility), structurally identical to cdp-eval's check: GET http://127.0.0.1:9222/json/version returned JSON without webSocketDebuggerUrl. The two utilities share the same launch requirement: Chromium must expose the CDP debugging endpoint on port 9222. Without it, no input can be injected.

Source

Thrown at open-computer/services/interface-service/utils/cdp-input.js:77

    ws.on("message", handler);
    ws.send(JSON.stringify(msg));
  });
}

function sleep(ms) {
  return new Promise((r) => setTimeout(r, ms));
}

// Randomized human-like delay between keystrokes
function keystrokeDelay() {
  return 30 + Math.floor(Math.random() * 60);
}

async function main() {
  const versionRaw = await httpGet("http://127.0.0.1:9222/json/version");
  const version = JSON.parse(versionRaw);
  const browserWsUrl = version.webSocketDebuggerUrl;
  if (!browserWsUrl) throw new Error("No webSocketDebuggerUrl — is Chromium running?");

  const ws = await new Promise((resolve, reject) => {
    const socket = new WebSocket(browserWsUrl);
    const t = setTimeout(() => reject(new Error("WS connect timeout")), 5000);
    socket.on("open", () => { clearTimeout(t); resolve(socket); });
    socket.on("error", (err) => { clearTimeout(t); reject(err); });
  });

  try {
    // Find target page
    const { targetInfos } = await cdpSend(ws, "Target.getTargets");
    const pages = targetInfos.filter(
      (t) => t.type === "page" && !t.url.startsWith("chrome://") && !t.url.startsWith("devtools://")
    );
    if (pages.length === 0) throw new Error("No browser pages open.");

    // Determine target URL filter (always last arg if it doesn't look like a coordinate/text)
    let targetUrl = "";

View on GitHub (pinned to 526360e320)

Solutions

1. Fully quit Chrome, then relaunch with --remote-debugging-port=9222.
2. Verify GET http://127.0.0.1:9222/json/version contains webSocketDebuggerUrl.
3. Use the open-computer launcher to start Chromium so the flags are applied.
4. Ensure no other Chrome instance is holding the profile/port.

Example fix

# before — existing Chrome without debugging
# (webSocketDebuggerUrl absent)

# after — fresh launch with debugging
killall chrome || taskkill /F /IM chrome.exe
chromium-browser --remote-debugging-port=9222 --remote-allow-origins=*

// Same probe as cdp-eval: confirm webSocketDebuggerUrl before injecting input.
async function cdpInputReady() {
  try {
    const v = JSON.parse(await httpGet('http://127.0.0.1:9222/json/version'));
    return typeof v.webSocketDebuggerUrl === 'string';
  } catch { return false; }
}

if (!await cdpInputReady()) {
  console.error('Relaunch Chromium with --remote-debugging-port=9222 (quit existing instances first).');
  process.exit(2);
}

When it happens

Trigger: Chromium launched without --remote-debugging-port; another process answering on 9222 with a non-Chromium response; a Chrome variant (e.g. some embedded webviews) that omits webSocketDebuggerUrl from the version JSON.

Common situations: User switched to a system Chrome that was already running without debugging flags (Chrome refuses to enable debugging on an existing instance); Chrome was started by a desktop shortcut without the flag; the open-computer launcher was bypassed.

Related errors

• No webSocketDebuggerUrl — is Chromium running?
• No browser pages open.
• No browser tab matching "${targetUrl}". Open tabs: ${openTab
• QEMU directory not found: ${dir} Contents of ${parent}: ${co
• No browser pages open.

AI-assisted analysis of Mintplex-Labs/anything-llm@526360e320 (2026-08-13). Data as JSON: /api/errors/3ed04a3474d686bb. Report an issue: GitHub.