browser-tools-mcp in Cursor: 'Error validating server identity' after macOS update — fix?
After updating macOS to 15.3.1, the browser-tools-mcp Chrome extension (Chrome 134.0.6998.89 arm64) disappeared, and MCP requests fail with the error 'Error validating server identity' for the browser-tools-mcp server in Cursor. Updating the MCP server in Cursor did not help, nor did removing the package and clearing the NPX cache. Is there a known fix or a required reinstall sequence?
Originally asked on GitHub: https://github.com/AgentDeskAI/browser-tools-mcp/issues/77
4 answers
The issue is closed as completed, but no code change was posted — the only confirmed resolution in the thread is a full cleanup and reinstall, so treat it as a workaround rather than a patch. The reporter's own attempts (removing the package, clearing the NPX cache, updating the MCP server in Cursor) were not enough on their own.
The sequence that worked in the thread:
- Uninstall the browser-tools-server package.
- Remove the Chrome extension from the browser.
- Delete the browser cache.
- Start the server manually in a terminal:
npx @agentdeskai/browser-tools-server@1.2.0. - Re-install the Chrome extension.
After that, the extension connected and requests worked again.
One Windows user with Cline/Claude Desktop hit the same kind of failure: the server started correctly, but the extension threw
Could not establish connection. Receiving end does not exist.Their MCP config pointed directly at the packaged entry point (...\@agentdeskai\browser-tools-server\dist\lighthouse\index.js) with--host localhost --port 3025, and the server reportedAggregator listening on http://0.0.0.0:3025, yet the extension still could not connect — so a running server alone does not mean the extension will pair. That report included no resolution, so the cleanup sequence above is the only confirmed fix.General advice: if the extension disappears again after a macOS or Chrome update, check that the extension is enabled and that the server port in your client config matches the port the server was started on before doing the full reinstall.
Did this work for you?What @joshrobertsv2 tried on GitHub (Worked)
Uninstalled the package, removed the Chrome extension, cleared the browser cache, ran
npx @agentdeskai/browser-tools-server@1.2.0, then re-installed the extension. The issue was resolved.Did this work for you?What a GitHub user tried on GitHub (Didn't work)
After the macOS update, removed the package and cleared the NPX cache, then updated the MCP server in Cursor. Requests still failed with an identity validation error.
Source: https://github.com/AgentDeskAI/browser-tools-mcp/issues/77 (opens external site)
Did this work for you?What @linm1 tried on GitHub (Outcome unclear)
On Windows with Cline/Claude Desktop, pointed the MCP config at the packaged
dist/lighthouse/index.jswith--port 3025, and started the server withnpx @agentdeskai/browser-tools-server@1.2.0. The server reported the port available, but the extension still threwCould not establish connection. Receiving end does not exist.Did this work for you?
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