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docs: add Chrome 142+ Private Network Access troubleshooting #1559

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docs: add Chrome 142+ Private Network Access troubleshooting
niilooy Nov 21, 2025
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47 changes: 47 additions & 0 deletions src/langsmith/troubleshooting-studio.mdx
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Expand Up @@ -36,6 +36,53 @@ Use this URL in Safari to load Studio. Here, the `baseUrl` parameter specifies y

Chrome and other Chromium browsers allow HTTP on localhost. Use `langgraph dev` without additional configuration.

## Chrome connection issues

Starting with Chrome version 142, you may experience "Failed to initialize Studio" errors with "TypeError: Failed to fetch" when trying to connect [LangSmith Studio](/langsmith/studio) to your local development server via [`langgraph dev`](/langsmith/cli). This occurs even when the API server at `http://127.0.0.1:2024/docs` loads successfully.

**Root Cause:** Chrome 142 fully enforces the Private Network Access (PNA) specification with no fallback, which blocks HTTPS sites (like `https://smith.langchain.com`) from accessing HTTP localhost servers by default.

### Symptoms

- Running `langgraph dev` starts the server successfully.
- Navigating to `http://127.0.0.1:2024/docs` shows the API documentation correctly.
- LangSmith Studio at `https://smith.langchain.com` shows: "Failed to initialize Studio - Please verify if the API server is running or accessible from the browser. TypeError: Failed to fetch".
- Browser console shows errors like: `Permission was denied for this request to access the 'unknown' address space`.

### Solution: Allow local network access in Chrome

1. Open LangSmith Studio at `https://smith.langchain.com` in Chrome.
2. Click the **lock icon** (or site information icon) to the left of the address bar.
3. Look for the **"Local network access"** option in the dropdown.
4. Change the setting from **"Ask (default)"** or **"Block"** to **"Allow"**.
5. Reload the page.

Studio should now connect to your local development server successfully.

### Additional troubleshooting

**Check for browser extension conflicts**

Browser extensions (especially Ollama Chrome extension or AI model extensions) can interfere with localhost connections:

1. Disable all browser extensions temporarily.
2. Restart Chrome.
3. Try connecting to Studio again.
4. If it works, re-enable extensions one by one to identify the culprit.

**Verify dependencies are up to date**

```shell
pip install -U "langgraph-cli[inmem]"
```

**Clear browser cache and site data**

1. In Chrome, go to **Settings** > **Privacy and Security** > **Site Settings**.
2. Find `https://smith.langchain.com` in the list.
3. Click **Clear data**.
4. Restart Chrome and try again.

## Brave Connection Issues

Brave blocks plain-HTTP traffic on localhost when Brave Shields are enabled. When running Studio with `langgraph dev`, you may see "Failed to load assistants" errors.
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