[Bug]: Claude Desktop is getting invalid type from mcp-context-forge gateway

[playground]

@kevalmahajan

🐞 Bug Summary

This was working a few of weeks ago, today I'm getting these errors

Fatal error: ServerError: HTTP 404: Invalid OAuth error response: [
  {
    "code": "invalid_type",
    "expected": "string",
    "received": "undefined",
    "path": [
      "error"
    ],
    "message": "Required"
  }
]

---

🧩 Affected Component

Select the area of the project impacted:

• mcpgateway - API
• mcpgateway - UI (admin panel)
• mcpgateway.wrapper - stdio wrapper
• Federation or Transports
• CLI, Makefiles, or shell scripts
• Container setup (Docker/Podman/Compose)
• Other (explain below)

---

🔁 Steps to Reproduce

1. here is the claude_desktop_config.json that was working a few weeks ago

{
  "mcpServers": {
    "open-horizon-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "http://localhost:4444/servers/224831b6cd344fb6b35179401ee8b7cc/mcp",
        "--header",
        "exchange-org:<orgId>",
        "--header",
        "exchange-url:http://open-horizon.lfedge.iol.unh.edu:3090/v1/orgs",
        "--header",
        "exchange-credential:<your_credential",
        "--header",
        "Authorization:Bearer *****************"
      ]
    }
  }
}

3. ...
4. ...

---

🤔 Expected Behavior

Claude Desktop should be able to discover this mcp server and tools

---

📓 Logs / Error Output

[49584] Recursively reconnecting for reason: falling-back-to-alternate-transport
[49584] [49584] Connecting to remote server: http://localhost:4444/servers/224831b6cd344fb6b35179401ee8b7cc/mcp
[49584] Using transport strategy: sse-only
[49584] Connection error: ServerError: HTTP 404: Invalid OAuth error response: [
  {
    "code": "invalid_type",
    "expected": "string",
    "received": "undefined",
    "path": [
      "error"
    ],
    "message": "Required"
  }
]. Raw body: {"detail":"Not Found"}
    at parseErrorResponse (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:12229:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async registerClient (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:12617:11)
    at async authInternal (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:12272:29)
    at async auth (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:12235:12)
    at async SSEClientTransport._authThenStart (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:13046:16)
    at async SSEClientTransport.start (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:13136:12)
    at async connectToRemoteServer (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/chunk-AKJME7CQ.js:13838:7)
    at async runProxy (file:///Users/jeff/.npm/_npx/705d23756ff7dacc/node_modules/mcp-remote/dist/proxy.js:141:29) {
  errorUri: undefined
}
[49584] Fatal error: ServerError: HTTP 404: Invalid OAuth error response: [
  {
    "code": "invalid_type",
    "expected": "string",
    "received": "undefined",
    "path": [
      "error"
    ],
    "message": "Required"
  }
]

---

🧠 Environment Info

You can retrieve most of this from the /version endpoint.

---

[crivetimihai]

Hi, thanks for checking. Can you test if:

1. The previous release 0.7.0, or 0.8.0 still work?
2. Does Fully implement MCP Spec 2025-06-18 #1343 address the issues?

Wondering if something changed in the client implementation.

Thanks!