Chrome extension not connecting: Browser extension is not connected

[Gandy2025]

Description

The Chrome browser extension (claude-in-chrome) consistently fails to connect with the error:

Browser extension is not connected. Please ensure the Claude browser extension is installed and running...

Environment

• Claude Code: v2.1.87 (installed via homebrew/npm global)
• OS: macOS Darwin 25.0.0
• Chrome: v146
• Chrome Extension: Claude v1.0.64 (fcoeoabgfenejglbffodgkkbkcdhcgfn), installed in Profile 1
• Node: v20.19.5
• Auth: claude.ai (firstParty), same account on both CLI and browser
• Subscription: Max

Setup verified

• Native messaging host config exists at ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json
• Native host script at ~/.claude/chrome/chrome-native-host is executable and points to correct node binary and CLI path
• Extension has correct permissions including nativeMessaging
• allowed_origins matches the extension ID
• Logged into the same account (gandyxiong@gmail.com) on both CLI (claude auth status) and claude.ai in Chrome

Steps attempted

1. Ran /login in Claude Code — login successful
2. Installed/verified extension in Chrome Profile 1
3. Toggled extension off and back on in chrome://extensions
4. Fully quit Chrome (Cmd+Q) and relaunched — multiple times
5. Verified claude.ai is open and logged in within the same Chrome profile
6. Called mcp__claude-in-chrome__tabs_context_mcp repeatedly — always returns "Browser extension is not connected"

Expected behavior

tabs_context_mcp should detect the Chrome extension and return tab information.

Actual behavior

Every call returns the "Browser extension is not connected" error, despite all configuration appearing correct.

🤖 Generated with Claude Code

[github-actions]

Found 3 possible duplicate issues:

1. claude-in-chrome: Browser extension not connected despite native host running (macOS 26.4, Claude Code 2.1.86) #40174
2. Claude in Chrome extension fails to connect on macOS (Chrome 146.0) #37684
3. Claude in Chrome: 'Browser extension is not connected' despite correct setup (macOS, Claude Desktop coexistence) #36471

This issue will be automatically closed as a duplicate in 3 days.

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🤖 Generated with Claude Code

[p11studio]

Root cause found: Claude Code was authenticated via API key instead of subscription, which blocks Chrome integration. Chrome only works with subscription plans — so even with everything correctly configured (same account, extension installed, correct profile), the connection never establishes.
How to identify this: Inside a Claude Code session, run /usage. If it says "only available for subscription plans", you're in API key mode and Chrome won't connect.
Solution that worked:

Inside Claude Code session run /login, or from terminal run claude logout then claude login
This forces re-authentication with your subscription account
Chrome extension connects immediately after

What was causing API key mode in my case:

A ANTHROPIC_API_KEY export line in ~/.zshrc pointing to a file that no longer existed ($(cat ~/.anthropic_api_key)) — the variable appeared empty with echo $ANTHROPIC_API_KEY but was still interfering
Running multiple Claude Code instances simultaneously (terminal + Cursor) can also cause auth conflicts

TL;DR: Before troubleshooting native hosts, profiles, or reinstalling the extension — check if /usage works. If it doesn't, re-authenticate with claude logout + claude login. That's it.

[KevinVanDriel-Perpetuals]

Additional root cause found: Password manager extensions (Dashlane, 1Password, etc.)

When using computer (click), javascript_tool, or screenshot on pages with login forms, password manager extensions inject overlays that intercept the interaction. The error message is:

Cannot access a chrome-extension:// URL of different extension

This is NOT the Claude extension failing to connect — it's another extension's popup/overlay stealing focus from the page.

Workaround: Send a key: Escape action before clicking or executing JS to dismiss the password manager popup. read_page and form_input still work fine (they use the accessibility tree, not page scripting).

Tested with: Dashlane on macOS Chrome, Claude Code v2.1.90.

[dorukardahan]

one more data point from my setup on macOS.

i had a case where CLI auth was fine, the native host manifest was fine, and the native host binary was also fine. The failing part was the extension side. After clearing the extension local state, there was no bridge socket and no active connection yet. Then i clicked the Claude extension icon once. That woke the service worker, started the native host process, created /tmp/claude-mcp-browser-bridge-doruk/70509.sock, and after that tabs_context_mcp returned a normal tab context.

So one failure mode behind "browser extension is not connected" seems to be this: the CLI and host can be healthy, but the extension service worker and extension state are still not ready. In my case the chain only came back after explicit extension interaction. This may be more likely when switching between multiple Claude accounts on one Chrome profile, because the extension state is shared on the browser side.