[MCP servers “Failed to connect” on Windows 11 (Node 22, npm 11.5.1, Claude CLI 1.0.62)]

Try running the MCP servers using absolute paths through Node.js directly.

As an example:

claude mcp add mcp-gitlab \
  -e GITLAB_PERSONAL_ACCESS_TOKEN="xxxxx" \
  -e GITLAB_PROJECT_ID="123456" \
  -- \
  node /home/me/.nvm/versions/node/v22.17.0/lib/node_modules/@zereight/mcp-gitlab/build/index.js

It's not a fix, but it's the workaround that is currently working for me.

Hope it helps.

Try running the MCP servers using absolute paths through Node.js directly. As an example: `` claude mcp add mcp-gitlab \ -e GITLAB_PERSONAL_ACCESS_TOKEN="xxxxx" \ -e GITLAB_PROJECT_ID="123456" \ -- \ node /home/me/.nvm/versions/node/v22.17.0/lib/node_modules/@zereight/mcp-gitlab/build/index.js `` It's not a fix, but it's the workaround that is currently working for me. Hope it helps.

Thanks for the workaround, though I notice the path you provided is Unix-style while the issue is specifically about Windows 😅 More importantly, hardcoding absolute paths defeats the purpose of having a proper CLI tool.
Hopefully anthropic will sooner fix this issue

I had a similar issue. Running claude doctor gave me this warning: Windows requires 'cmd /c' wrapper to execute npx

I've updated my .mcp.json to this and it works now:

{
  "mcpServers": {
    "playwright": {
      "command": "cmd",
      "args": ["/c", "npx", "@playwright/mcp@latest"],
      "type": "stdio"
    }
  }
}

wonder if bunx would work with this

{
 "mcpServers": {
        "mcp_server_mysql": {
          "command": "cmd",
          "args": [
            "/c",
            "bunx",
            "@benborla29/mcp-server-mysql"
          ],
          "env": {
            "MYSQL_HOST": "127.0.0.1",
            "MYSQL_PORT": "3306",
            "MYSQL_USER": "lms",
            "MYSQL_PASS": "lmsroot",
            "MYSQL_DB": "lms",
            "ALLOW_INSERT_OPERATION": "false",
            "ALLOW_UPDATE_OPERATION": "false",
            "ALLOW_DELETE_OPERATION": "false"
          }
        }
      }
}

mcp_server_mysql: cmd /c bunx @benborla29/mcp-server-mysql - ✗ Failed to connect

claude doctor

Claude CLI Diagnostic
Currently running: npm-global (1.0.67)
Path: C:\Program Files\nodejs\node.exe
Invoked: C:\Users\YuenSzeHong\AppData\Roaming\npm\node_modules\@anthropic-ai\claude-code\cli.js
Config install method: unknown
Auto-updates enabled: true
Update permissions: Yes
Press Enter to continue…

I had a similar issue. Running claude doctor gave me this warning: Windows requires 'cmd /c' wrapper to execute npx I've updated my .mcp.json to this and it works now: `` { "mcpServers": { "playwright": { "command": "cmd", "args": ["/c", "npx", "@playwright/mcp@latest"], "type": "stdio" } } } ``

✅ ISSUE RESOLVED - Windows 11 MCP Connection Problem SOLVED!

I'm happy to report that this Windows 11 MCP connection issue has been completely resolved! All three MCP servers (context7, playwright, firecrawl) are now successfully connecting and fully operational.

🎯 Root Cause & Solution

Root Cause: Windows requires a cmd /c wrapper for npm subprocess execution, which the Claude CLI wasn't handling automatically.

Working Solution: Use the cmd /c wrapper format when adding MCP servers:

claude mcp add server-name -- cmd /c npx package-name

Example working commands:

claude mcp add context7 -- cmd /c npx @upstash/context7-mcp
claude mcp add playwright -- cmd /c npx @playwright/mcp
claude mcp add firecrawl -- cmd /c npx firecrawl-mcp

🏆 Acknowledgments & Special Thanks

🌟 Special recognition to @pouliens (Paulius Tvaranavicius) - You found the actual solution! Your discovery that claude doctor shows the warning "Windows requires 'cmd /c' wrapper to execute npx" was the key breakthrough. Your .mcp.json configuration example with the cmd /c wrapper format solved the core issue. Thank you for your persistence and technical insight! 🙏

Thanks to all contributors who helped troubleshoot:

• @vmadman (Luke Chavers): Thank you for the initial workaround attempt using absolute paths with node directly. While it wasn't the final solution, it helped confirm the npm binaries were functional and pointed us toward a subprocess execution issue. Your willingness to share a working approach helped move the troubleshooting forward.
• @YuenSzeHong (Yuen Sze Hong): Thanks for your valuable feedback pointing out that the Unix-style paths wouldn't work on Windows and that hardcoding absolute paths defeats the purpose of having a proper CLI tool. You also tested alternative approaches like bunx and helped validate that this was a Windows-specific execution problem. Your critical analysis kept us focused on finding a proper solution.

📋 Final Status - All MCP Servers Connected

claude mcp list
Checking MCP server health...
context7: cmd /c npx @upstash/context7-mcp - ✓ Connected
playwright: cmd /c npx @playwright/mcp - ✓ Connected  
firecrawl: cmd /c npx firecrawl-mcp - ✓ Connected

🔧 For Future Windows 11 Users

If you encounter "Failed to connect" with MCP servers on Windows 11:

1. Run claude doctor to check for the Windows 'cmd /c' wrapper warning
2. Remove existing broken servers: claude mcp remove server-name
3. Re-add using the Windows format: claude mcp add server-name -- cmd /c npx package-name
4. Verify with claude mcp list - should show "✓ Connected"

This solution should work for any npm-installed MCP server on Windows 11.

---

Closing this issue as RESOLVED. Thanks again to everyone who contributed to solving this Windows-specific MCP connection problem! 🎉

— Carlos Gattorno (@CFA-Fintech)

## ✅ ISSUE RESOLVED - Windows 11 MCP Connection Problem SOLVED! I'm happy to report that this Windows 11 MCP connection issue has been completely resolved! All three MCP servers (context7, playwright, firecrawl) are now successfully connecting and fully operational. ### 🎯 Root Cause & Solution Root Cause: Windows requires a cmd /c wrapper for npm subprocess execution, which the Claude CLI wasn't handling automatically. Working Solution: Use the cmd /c wrapper format when adding MCP servers: ``bash claude mcp add server-name -- cmd /c npx package-name ` **Example working commands**: `bash claude mcp add context7 -- cmd /c npx @upstash/context7-mcp claude mcp add playwright -- cmd /c npx @playwright/mcp claude mcp add firecrawl -- cmd /c npx firecrawl-mcp ` ### 🏆 **Acknowledgments & Special Thanks** **🌟 Special recognition to @pouliens (Paulius Tvaranavicius)** - You found the actual solution! Your discovery that claude doctor shows the warning "Windows requires 'cmd /c' wrapper to execute npx" was the key breakthrough. Your .mcp.json configuration example with the cmd /c wrapper format solved the core issue. Thank you for your persistence and technical insight! 🙏 **Thanks to all contributors who helped troubleshoot:** - **@vmadman (Luke Chavers)**: Thank you for the initial workaround attempt using absolute paths with node directly. While it wasn't the final solution, it helped confirm the npm binaries were functional and pointed us toward a subprocess execution issue. Your willingness to share a working approach helped move the troubleshooting forward. - **@YuenSzeHong (Yuen Sze Hong)**: Thanks for your valuable feedback pointing out that the Unix-style paths wouldn't work on Windows and that hardcoding absolute paths defeats the purpose of having a proper CLI tool. You also tested alternative approaches like bunx and helped validate that this was a Windows-specific execution problem. Your critical analysis kept us focused on finding a proper solution. ### 📋 **Final Status - All MCP Servers Connected** ` claude mcp list Checking MCP server health... context7: cmd /c npx @upstash/context7-mcp - ✓ Connected playwright: cmd /c npx @playwright/mcp - ✓ Connected firecrawl: cmd /c npx firecrawl-mcp - ✓ Connected ` ### 🔧 **For Future Windows 11 Users** If you encounter "Failed to connect" with MCP servers on Windows 11: 1. Run claude doctor to check for the Windows 'cmd /c' wrapper warning 2. Remove existing broken servers: claude mcp remove server-name 3. Re-add using the Windows format: claude mcp add server-name -- cmd /c npx package-name 4. Verify with claude mcp list` - should show "✓ Connected" This solution should work for any npm-installed MCP server on Windows 11. --- Closing this issue as RESOLVED. Thanks again to everyone who contributed to solving this Windows-specific MCP connection problem! 🎉 — Carlos Gattorno (@CFA-Fintech)

well, npx did work, but bunx don't work with the fix

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