Claude in Chrome extension not connecting on Windows despite MCP server showing "connected"

Status Closed — not planned

Maintainer reply ✓ Yes — localden

Activity 13 comments · opened Jan 27, 2026 · closed May 5, 2026

💡 Likely answer: A maintainer (localden, collaborator) responded on this thread — see the highlighted reply below.

Bug Description

The Claude in Chrome browser extension (v1.0.40) fails to connect to Claude Code on Windows. The MCP server shows as "connected" in Claude Code's /mcp status, but every call to tabs_context_mcp returns "Browser extension is not connected."

Steps to Reproduce

Install Claude in Chrome extension (v1.0.40) from the Chrome Web Store
Enable the extension with "On all sites" access
Start Claude Code CLI
Verify /mcp shows claude-in-chrome · connected
Attempt to use any mcp__claude-in-chrome__* tool (e.g., tabs_context_mcp)

Expected Behavior

tabs_context_mcp should return tab context information from the browser.

Actual Behavior

Every call returns: "Browser extension is not connected. Please ensure the Claude browser extension is installed and running."

Troubleshooting Attempted

Restarted PC
Restarted Chrome multiple times
Restarted Claude Code multiple times
Killed all Chrome processes and relaunched
Verified extension is enabled with correct permissions
Confirmed MCP server shows as connected in Claude Code
Extension has "Communicate with cooperating native applications" permission

Environment

OS: Windows 11 Pro (NT 10.0.26200.0)
Chrome Extension: Claude in Chrome (Beta) v1.0.40
Extension ID: fcoeoabgfenejglbffodg

View original on GitHub ↗

13 Comments

github-actions[bot] · 7 months ago

Found 3 possible duplicate issues:

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🤖 Generated with Claude Code

mav33rick · 7 months ago

I have the same issue.

Bun crashed.

coryvirok · 7 months ago

I have the same issue on MacOS. However after disabling and enabling in Claude Code CLI a couple times, it started working.

Note: The browser tab group for CC CLI will be named "Claude MCP" vs just "Claude" for the in-browser experience.

ibrahim-descript · 7 months ago

I spent a lot of time on this today, now realizing that this is just a bug

StefSmeers · 7 months ago

I was using Claude Code v2.1.21 and Chrome extension v1.0.40.
I then installed Claude Code v2.1.7 again (stable version) and it seems to work fine then.

I also tested at what point it broke: everything worked up until Claude Code v2.1.19. It broke with v2.1.20.

So recommended fix everyone with this issue:
Go to your terminal and run this command: claude install 2.1.19 or claude install 2.1.7 if you want the stable version

revilasas · 7 months ago

Thanks you @StefSmeers ! You solved my problem ! last version claude --> 2,1,19 now working.

also working : npm uninstall -g @anthropic-ai/claude-code
npm install -g @anthropic-ai/claude-code@2.0.76

DanSoQt · 7 months ago

Also experiencing this on v2.1.23

salvadorplj · 7 months ago

Also hitting this on Windows 11, Claude Code v2.1.23.

Dug into the root cause: the native messaging host (claude.exe --chrome-native-host) crashes immediately with a Bun v1.3.5 panic:

[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \\.\pipe\claude-mcp-browser-bridge-<user>

panic(main thread): Internal assertion failure
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

https://bun.report/1.3.5/e_11e86cebEugggC++08F+mvBoxhkf0389e__0shkwCA0eNrzzCtJLcpLzFFILC5OLSrJzM9TSEvMzCktSgUAiSkKPg

The registry entry and manifest at %APPDATA%\Claude Code\ChromeNativeHost\ are correct, and the batch wrapper at %USERPROFILE%\.claude\chrome\chrome-native-host.bat is fine — it's the executable itself that panics before it can establish the named pipe.

Confirmed the downgrade to v2.1.19 per @StefSmeers fixes it.

`claude install 2.1.19` to downgrade an OS install instead of npm.

This should be prioritized since it completely breaks Chrome integration on Windows for v2.1.20+.

kimchi-developer · 6 months ago

Root cause found and documented in #21791: The \ function (socket path discovery) doesn't return Windows named pipe path. Fix: add \ at the start of the function.

See detailed analysis: https://github.com/anthropics/claude-code/issues/21791#issuecomment-3838702991

bosmadev · 6 months ago

Root cause identified — \ never includes Windows named pipe paths (\), only tmpdir filesystem paths that can't reach named pipes. Full analysis and fix: #23828

bosmadev · 6 months ago

Update: Published the complete self-healing fix as open-source: bosmadev/claude — scripts/fix-chrome-native-host.py

SessionStart hook auto-repairs all 3 Windows Chrome bugs on every launch. See #23828 for full details.

localden collaborator · 3 months ago

Thank you for your report — we are currently in the process of triaging MCP-related issues and this one appears to describe the same problem as #21337. To keep the discussion and any fix in one place, we're consolidating into that issue and closing this one. If you have logs, repro steps, or environment details that aren't already covered in #21337, please add them there — it'll help us track this down faster.

github-actions[bot] · 2 months ago

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.