MCP Client seems to be broken

Questions
1

Describe the problem/error/question

I’m getting a “Could not connect to your MCP server” error when calling one from N8N Cloud using the MCP Client tool

What is the error message (if any)?


NodeOperationError: Error in sub-node MCP Client at ExecuteContext.getInputConnectionData (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/n8n-core@file+packages+core_@[email protected]_@[email protected]_08b575bec2313d5d8a4cc75358971443/node_modules/n8n-core/src/execution-engine/node-execution-context/utils/get-input-connection-data.ts:302:11) at processTicksAndRejections (node:internal/process/task_queues:105:5) at ExecuteContext.getInputConnectionData (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/n8n-core@file+packages+core_@[email protected]_@[email protected]_08b575bec2313d5d8a4cc75358971443/node_modules/n8n-core/src/execution-engine/node-execution-context/execute-context.ts:178:10) at getConnectedTools (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/@n8n+n8n-nodes-langchain@file+packages+@n8n+nodes-langchain_3b8ccb8a5e2a08fdc65c7a64d454d480/node_modules/@n8n/n8n-nodes-langchain/utils/helpers.ts:208:5) at getTools (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/@n8n+n8n-nodes-langchain@file+packages+@n8n+nodes-langchain_3b8ccb8a5e2a08fdc65c7a64d454d480/node_modules/@n8n/n8n-nodes-langchain/nodes/agents/Agent/agents/ToolsAgent/common.ts:331:17) at /usr/local/lib/node_modules/n8n/node_modules/.pnpm/@n8n+n8n-nodes-langchain@file+packages+@n8n+nodes-langchain_3b8ccb8a5e2a08fdc65c7a64d454d480/node_modules/@n8n/n8n-nodes-langchain/nodes/agents/Agent/agents/ToolsAgent/V2/execute.ts:222:18 at async Promise.allSettled (index 0) at ExecuteContext.toolsAgentExecute (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/@n8n+n8n-nodes-langchain@file+packages+@n8n+nodes-langchain_3b8ccb8a5e2a08fdc65c7a64d454d480/node_modules/@n8n/n8n-nodes-langchain/nodes/agents/Agent/agents/ToolsAgent/V2/execute.ts:290:24) at ExecuteContext.execute (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/@n8n+n8n-nodes-langchain@file+packages+@n8n+nodes-langchain_3b8ccb8a5e2a08fdc65c7a64d454d480/node_modules/@n8n/n8n-nodes-langchain/nodes/agents/Agent/V2/AgentV2.node.ts:131:10) at WorkflowExecute.executeNode (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/n8n-core@file+packages+core_@[email protected]_@[email protected]_08b575bec2313d5d8a4cc75358971443/node_modules/n8n-core/src/execution-engine/workflow-execute.ts:1254:8) at WorkflowExecute.runNode (/usr/local/lib/node_modules/n8n/node_modules/.pnpm/n8n-core@file+packages+core_@[email protected]_@[email protected]_08b575bec2313d5d8a4cc75358971443/node_modules/n8n-core/src/execution-engine/workflow-execute.ts:1428:11) at /usr/local/lib/node_modules/n8n/node_modules/.pnpm/n8n-core@file+packages+core_@[email protected]_@[email protected]_08b575bec2313d5d8a4cc75358971443/node_modules/n8n-core/src/execution-engine/workflow-execute.ts:1761:27 at /usr/local/lib/node_modules/n8n/node_modules/.pnpm/n8n-core@file+packages+core_@[email protected]_@[email protected]_08b575bec2313d5d8a4cc75358971443/node_modules/n8n-core/src/execution-engine/workflow-execute.ts:2338:11

Please share your workflow

({
  "nodes": [
    {
      "parameters": {},
      "type": "@n8n/n8n-nodes-langchain.memoryBufferWindow",
      "typeVersion": 1.3,
      "position": [
        -32,
        160
      ],
      "id": "203607d3-ad2a-49a8-b0bf-5de843f61fd4",
      "name": "Simple Memory"
    },
    {
      "parameters": {
        "model": {
          "__rl": true,
          "value": "gpt-4.1-mini",
          "mode": "list",
          "cachedResultName": "gpt-4.1-mini"
        },
        "options": {}
      },
      "type": "@n8n/n8n-nodes-langchain.lmChatOpenAi",
      "typeVersion": 1.2,
      "position": [
        -160,
        160
      ],
      "id": "02fd6730-febf-4d1c-940d-a4661f9903ae",
      "name": "OpenAI Chat Model",
      "credentials": {
        "openAiApi": {
          "id": "yryzRHlgL1B1jx6h",
          "name": "OpenAI account"
        }
      }
    },
    {
      "parameters": {
        "endpointUrl": "https://api.githubcopilot.com/mcp/",
        "serverTransport": "httpStreamable",
        "options": {
          "timeout": 60000
        }
      },
      "type": "@n8n/n8n-nodes-langchain.mcpClientTool",
      "typeVersion": 1.1,
      "position": [
        96,
        160
      ],
      "id": "eb69f6ab-3835-4c74-9a3a-a590ea860134",
      "name": "MCP Client"
    }
  ],
  "connections": {
    "Simple Memory": {
      "ai_memory": [
        []
      ]
    },
    "OpenAI Chat Model": {
      "ai_languageModel": [
        []
      ]
    },
    "MCP Client": {
      "ai_tool": [
        []
      ]
    }
  },
  "pinData": {},
  "meta": {
    "templateCredsSetupCompleted": true,
    "instanceId": "fa89c65eccb4f33e65a4a7c851ec7a4911c2b39d316d1f433ea07069df902f77"
  }
}

Share the output returned by the last node

Item Index
0
n8n version
1.112.6 (Cloud)
Time
9/29/2025, 11:06:11 AM

Information on your n8n setup

  • Node type

    @n8n/n8n-nodes-langchain.mcpClientTool

    Node version

    1.1 (Latest)

    n8n version

    1.112.6 (Cloud)

5 Likes
2

Same here. I’m trying to connect n8n mcp client to n8n mcp server. I tried all the configuration I can find in this community and still I received an error message
Error in sub-node ‘MCP Client‘

Could not connect to your MCP server
I’m self hosting on hostinger with docker.
MCP server is listening
GZIP is not active
MCP URL is reachable

it don’t even reach the MCP server, it’s denied before.
I’m open to any clue

n8nVersion: 1.112.6

  • platform: docker (self-hosted)
  • nodeJsVersion: 22.19.0
  • database: sqlite
  • executionMode: regular
  • concurrency: -1
  • license: enterprise (production)

Thanks

3

I am also having the same issue

4

Tried n8n MCP client + n8n mcp server trigger (in separate workflows). Both SSE and HTTP Streamable setups works to list tools.

Docker, self-hosted. 1.112.6.

2 Likes
5

thanks Jabbson, I’m using the cloud version and there’s almost nothing in the console I can find with any relevant debug logs. Secondarily, I’m hosting this MCP in the cloud and have verified connectivity with the MCPInspector tool locally, and verified successful N8N traffic from the gateway. Any tips on how I could debug this further?

6

From the attached workflow I see you are trying to connect to https://api.githubcopilot.com/mcp/

have you provided an authentication in the node which would allow github to know who you are?

7

That is a placeholder, as I did not want to expose my private MCP to a forum on the internet. As I mentioned in my above comment I can successfully connect to the MCP server using the public internet and authentication using the MCP Inspector tool running locally. Additionally, I do not get an error message indicating auth is the issue from within the node. Several others have noted they are also not able to leverage the MCP client tool in N8N. I’ve also seen several posts from earlier this year where this happened and then "magically” went away. I’d love to have access to the debug logs for the http client to know what is causing the node to error, but I only get a stacktrace that isn’t super helpful to me.

8

It seems like the root of the issue is some inconsistency in Session handling between the MCP Client Tool and the remote MCP. This is a bit of an up in the air topic in MCP, but we’ve been running successfully for most of the day knock on wood and will continue testing.

1 Like
9

Still not resolve ?

I have the same exact problem… Hosting in hostinger… I tried everything