--- name: troubleshooting description: Uses Chrome DevTools MCP and documentation to troubleshoot connection and target issues. Trigger this skill when list_pages, new_page, or navigate_page fail, or when the server initialization fails. --- ## Troubleshooting Wizard You are acting as a troubleshooting wizard to help the user configure and fix their Chrome DevTools MCP server setup. When this skill is triggered (e.g., because `list_pages`, `new_page`, or `navigate_page` failed, or the server wouldn't start), follow this step-by-step diagnostic process: ### Step 1: Find and Read Configuration Your first action should be to locate and read the MCP configuration file. Search for the following files in the user's workspace: `.mcp.json`, `gemini-extension.json`, `.claude/settings.json`, `.vscode/launch.json`, or `.gemini/settings.json`. If you find a configuration file, read and interpret it to identify potential issues such as: - Incorrect arguments or flags. - Missing environment variables. - Usage of `--autoConnect` in incompatible environments. If you cannot find any of these files, only then should you ask the user to provide their configuration file content. ### Step 2: Triage Common Connection Errors Before reading documentation or suggesting configuration changes, check if the error message matches one of the following common patterns. #### Error: `Could not find DevToolsActivePort` This error is highly specific to the `--autoConnect` feature. It means the MCP server cannot find the file created by a running, debuggable Chrome instance. This is not a generic connection failure. Your primary goal is to guide the user to ensure Chrome is running and properly configured. Do not immediately suggest switching to `--browserUrl`. Follow this exact sequence: 1. **Ask the user to confirm that the correct Chrome version** (e.g., "Chrome Canary" if the error mentions it) is currently running. 2. **If the user confirms it is running, instruct them to enable remote debugging.** Be very specific about the URL and the action: "Please open a new tab in Chrome, navigate to `chrome://inspect/#remote-debugging`, and make sure the 'Enable remote debugging' checkbox is checked." 3. **Once the user confirms both steps, your only next action should be to call the `list_pages` tool.** This is the simplest and safest way to verify if the connection is now successful. Do not retry the original, more complex command yet. 4. **If `list_pages` succeeds, the problem is resolved.** If it still fails with the same error, then you can proceed to the more advanced steps like suggesting `--browserUrl` or checking for sandboxing issues. #### Symptom: Server starts but creates a new empty profile If the server starts successfully but `list_pages` returns an empty list or creates a new profile instead of connecting to the existing Chrome instance, check for typos in the arguments. - **Check for flag typos:** For example, `--autoBronnect` instead of `--autoConnect`. - **Verify the configuration:** Ensure the arguments match the expected flags exactly. #### Symptom: Missing Tools / Only 9 tools available If the server starts successfully but only a limited subset of tools (like `list_pages`, `get_console_message`, `lighthouse_audit`, `take_heapsnapshot`) are available, this is likely because the MCP client is enforcing a **read-only mode**. All tools in `chrome-devtools-mcp` are annotated with `readOnlyHint: true` (for safe, non-modifying tools) or `readOnlyHint: false` (for tools that modify browser state, like `emulate`, `click`, `navigate_page`). To access the full suite of tools, the user must disable read-only mode in their MCP client (e.g., by exiting "Plan Mode" in Gemini CLI or adjusting their client's tool safety settings). #### Symptom: Extension tools are missing or extensions fail to load If the tools related to extensions (like `install_extension`) are not available, or if the extensions you load are not functioning: 1. **Check for the `--categoryExtensions` flag**: Ensure this flag is passed in the MCP server configuration to enable the extension category tools. 2. **Make sure the MCP server in configured to launch Chrome instead of connecting to an instance**: Chrome before 149 is not able to load extensions when connecting to an existing instance (`--auto-connect`, `--browserUrl`). #### Other Common Errors Identify other error messages from the failed tool call or the MCP initialization logs: - `Target closed` - "Tool not found" (check if they are using `--slim` which only enables navigation and screenshot tools). - `ProtocolError: Network.enable timed out` or `The socket connection was closed unexpectedly` - `Error [ERR_MODULE_NOT_FOUND]: Cannot find module` - Any sandboxing or host validation errors. ### Step 3: Read Known Issues Read the contents of https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/main/docs/troubleshooting.md to map the error to a known issue. Pay close attention to: - Sandboxing restrictions (macOS Seatbelt, Linux containers). - WSL requirements. - `--autoConnect` handshakes, timeouts, and requirements (requires **running** Chrome 144+). ### Step 4: Formulate a Configuration Based on the exact error and the user's environment (OS, MCP client), formulate the correct MCP configuration snippet. Check if they need to: - Pass `--browser-url=http://127.0.0.1:9222` instead of `--autoConnect` (e.g. if they are in a sandboxed environment like Claude Desktop). - Enable remote debugging in Chrome (`chrome://inspect/#remote-debugging`) and accept the connection prompt. **Ask the user to verify this is enabled if using `--autoConnect`.** - Add `--logFile ` to capture debug logs for analysis. - Increase `startup_timeout_ms` (e.g. to 20000) if using Codex on Windows. _If you are unsure of the user's configuration, ask the user to provide their current MCP server JSON configuration._ ### Step 5: Run Diagnostic Commands If the issue is still unclear, run diagnostic commands to test the server directly: - Run `npx chrome-devtools-mcp@latest --help` to verify the installation and Node.js environment. - If you need more information, run `DEBUG=* npx chrome-devtools-mcp@latest --logFile=/tmp/cdm-test.log` to capture verbose logs. Analyze the output for errors. ### Step 6: Check GitHub for Existing Issues If https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/main/docs/troubleshooting.md does not cover the specific error, check if the `gh` (GitHub CLI) tool is available in the environment. If so, search the GitHub repository for similar issues: `gh issue list --repo ChromeDevTools/chrome-devtools-mcp --search "" --state all` Alternatively, you can recommend that the user checks https://github.com/ChromeDevTools/chrome-devtools-mcp/issues and https://github.com/ChromeDevTools/chrome-devtools-mcp/discussions for help.