Update: March 25, 2026 – As of this writing, this issue remains unresolved for many users following the February 2026 Claude Desktop update.
If you are a user of Anthropic’s Claude Desktop or Claude Code, you may have encountered the frustrating error message: “Could not connect to MCP server Claude in Chrome” (or mcp-registry).
This error effectively breaks browser automation, preventing Claude from interacting with your Chrome browser. Based on recent user reports and official debugging guides, here is a comprehensive look at why this happens and how to diagnose it.
Understanding the MCP Connection
The Model Context Protocol (MCP) is the backbone that allows Claude to talk to external tools like your Chrome browser. For this connection to work, several components must align perfectly:
The Chrome Extension: The “Claude in Chrome” extension must be installed and signed in.
The Native Messaging Host: This is a bridge (a small piece of software) that allows the Chrome extension to communicate with your operating system. Its configuration must be correct.
Claude Desktop/Code: The application must be able to discover and launch these services.
The mcp-registry: This is a foundational service that manages the discovery of all MCP tools. If it fails, all tools (including Chrome) become invisible to Claude.
Root Cause: A Confirmed February 2026 Regression
If your setup was working before but suddenly broke around mid-February 2026, you are experiencing a known regression. Multiple users have confirmed that after auto-updating to Claude Desktop version 1.1.3189 (build 2026-02-14), the mcp-registry and Claude in Chrome servers began failing to connect consistently.
Log analysis shows a distinct failure pattern: while local extensions launch correctly (Control Chrome typically succeeds), the “bridge-type” servers get stuck at the “connection requested” stage and never progress to “launching,” eventually timing out silently.
This appears to be a bug in how the Cowork VM communicates with the MCP bridge layer.
Broader MCP Issues in Version 1.1.3189
The Chrome connection problem is not the only issue introduced in this update. Users have reported that the same version broke other MCP tools as well, notably the Notion MCP server. In that case, object parameters were being incorrectly serialized as strings, causing tools to fail when receiving complex data structures.
This pattern suggests that version 1.1.3189 introduced a widespread regression in how Claude Desktop handles MCP communication, affecting multiple bridge-type and parameter-dependent servers.
Step-by-Step Troubleshooting Guide
Before diving into complex fixes, follow these systematic steps to diagnose the issue.
1. Initial Checks and Restarts
Sometimes, a simple state reset is all that is needed.
- Full Clean Restart: Quit both Chrome and Claude Desktop completely.
- Clear Temp Files: Delete the bridge socket directory. On macOS, this is located at
/tmp/claude-mcp-browser-bridge-$USER. - Relaunch Order: Launch Chrome first, ensure your profile is loaded, then launch Claude Desktop.
2. Verify Native Host Installation
The native messaging host manifest tells Chrome where to find the bridge. Its location must be exact.
- Check Manifest Location (macOS):
~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json - Verify Extension ID: Open the manifest file and ensure the
allowed_originsentry matches the exact Extension ID of your installed “Claude in Chrome” extension (usuallyfcoeoabgfenejglbffodgkkbkcdhcgfn). - Check for Conflicts: If you use both Claude Desktop and Claude Code, they may have competing native host files. Try disabling one by renaming it (e.g., adding
.bakto the filename).
3. Utilize Chrome DevTools in Claude Desktop
Claude Desktop has a hidden feature: Chrome DevTools for the app itself. This is invaluable for spotting client-side errors.
Enable DevTools: Run the following command in your terminal to create a settings file:
bashecho '{"allowDevTools": true}' > ~/Library/Application\ Support/Claude/developer_settings.json
Open DevTools: In Claude Desktop, press Command-Option-Shift-i.
Check the Console: Look for red error messages related to MCP or WebSocket connections.
4. Check the Logs
The main.log file provides the most detailed view of what is happening under the hood.
Tail the Logs: Open your terminal and run:
bash
tail -n 20 -F ~/Library/Logs/Claude/mcp*.log
Analyze the Output: Look for the specific MCP server names. Do you see entries like MCP Server connection requested for: Claude in Chrome followed by the same entry again a few seconds later?
This pattern of retries without a Launching or Running status indicates the connection is stuck.
(Note: If Control Chrome launches successfully but mcp-registry does not, you have confirmed you are experiencing the known regression).
For more advanced debugging techniques, refer to the [official MCP debugging guides] .”
Platform-Specific Issues
macOS
Most of the recent “Could not connect” errors are being reported on macOS, particularly on Apple Silicon machines. The issue seems deeply rooted in the latest Desktop app update.
Windows
On Windows, users have reported various MCP configuration failures, including issues with Docker named pipes, PATH environment variables, and file encoding (BOM) problems in configuration files.
For a comprehensive guide to resolving these Windows-specific issues, see [How to Fix Claude Cowork on Windows].
If you are experiencing connection failures on Windows, verify your MCP server configurations for these common pitfalls.
When All Else Fails: Advanced Workarounds
If the connection itself is solid, but the functionality is broken (e.g., Claude can open Chrome but can’t log into websites), you are facing a session persistence issue.
The Cookie Problem
It appears that when Claude uses Chrome via MCP, it often starts a fresh session that does not persist cookies. This means it cannot stay logged into websites, causing redirect loops on pages like WordPress admin dashboards.
Development Workaround
Until Anthropic fixes session persistence, developers have resorted to creative workarounds. For example, a WordPress developer created a “mu-plugin” that bypasses the login check entirely for local environments when a specific constant is defined.
This forces the site to recognize a specific test user without needing cookies.
Security Context
While troubleshooting, it is worth noting that recent security research has identified critical vulnerabilities in MCP servers, including RCE chains and SSRF risks. Always ensure you are using trusted extensions and tools.
Conclusion
The “Could not connect to MCP server Claude in Chrome” error is a confirmed regression from the February 2026 update that, as of March 25, 2026, remains unresolved by Anthropic.
This same update also introduced MCP communication issues affecting other tools like Notion, indicating a broader problem in how Claude Desktop handles bridge-type servers and complex parameters.
By methodically checking your installation, analyzing logs with DevTools, and ensuring all components are up-to-date, you can diagnose the issue. If the issue persists, it is likely the known bug; commenting on relevant GitHub issues helps prioritize a fix from Anthropic.
