From eab80f92d1194e1583c96346b3f4b534ae658f43 Mon Sep 17 00:00:00 2001 From: Niloy Ghosh Date: Fri, 21 Nov 2025 14:18:00 +0530 Subject: [PATCH 1/2] docs: add Chrome 142+ Private Network Access troubleshooting Add troubleshooting section for Chrome 142+ blocking localhost connections due to Private Network Access (PNA) enforcement. Includes solution to allow local network access in Chrome settings and additional troubleshooting steps. --- src/langsmith/troubleshooting-studio.mdx | 47 ++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/src/langsmith/troubleshooting-studio.mdx b/src/langsmith/troubleshooting-studio.mdx index 3ee179167a..4fe35f5ffb 100644 --- a/src/langsmith/troubleshooting-studio.mdx +++ b/src/langsmith/troubleshooting-studio.mdx @@ -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 to your local development server via `langgraph dev`. 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 + +The 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. From adb70b3bedc6284460eceaa6386b993b79c702fe Mon Sep 17 00:00:00 2001 From: Niloy Ghosh Date: Sat, 22 Nov 2025 01:24:30 +0530 Subject: [PATCH 2/2] Apply suggestions from code review Co-authored-by: Kathryn May <44557882+katmayb@users.noreply.github.com> --- src/langsmith/troubleshooting-studio.mdx | 50 ++++++++++++------------ 1 file changed, 25 insertions(+), 25 deletions(-) diff --git a/src/langsmith/troubleshooting-studio.mdx b/src/langsmith/troubleshooting-studio.mdx index 4fe35f5ffb..d02bfe51d3 100644 --- a/src/langsmith/troubleshooting-studio.mdx +++ b/src/langsmith/troubleshooting-studio.mdx @@ -36,52 +36,52 @@ 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 +## 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 to your local development server via `langgraph dev`. This occurs even when the API server at `http://127.0.0.1:2024/docs` loads successfully. +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` +- 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 +### 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 +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. -The Studio should now connect to your local development server successfully. +Studio should now connect to your local development server successfully. -### Additional Troubleshooting +### Additional troubleshooting -**Check for Browser Extension Conflicts** +**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 +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** +**Verify dependencies are up to date** ```shell pip install -U "langgraph-cli[inmem]" ``` -**Clear Browser Cache and Site Data** +**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 +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