Connect a k8s Spring boot MCP Server to n8n MCP Client node failed

Questions
1

Hello , I ve deployed n8n to OpenShift using the Community Helm Chart,

and developed a Custom Spring boot MCP Server that is deployed in the same Cluster , when I try to connect to the MCP Server from the n8n MCP Client node I get the error:

Error in sub-node ‘MCP Client‘

Could not connect to your MCP server

if I wget the sse url from within the n8n container I get 200ok .
and this is the error that I see in the container log (/home/node/.n8n/n8nEventLog.log)

“PartialExecutionToolExecutor”,“errorNodeType”:“@n8n/n8n-nodes-langchain.mcpClientTool”,“errorMessage”:“Error in sub-node MCP Client”}}

Information on your n8n setup

  • n8n version: 1.107.4
  • Database (default: SQLite): Postgres
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via: OpenShift

I would really appreciate your input . Thank you.

2

Hey @Bel_Sh Hope you are doing great! I’m not a K8s expert but are you running more than 1 web containers? Recently I faced a similar issue and I fixed it by reducing it!

Happy to read your comments!

3

Thank you for your reply. No it’s only one replica of a straight forward Spring boot mcp server. Is your server behind a proxy?

I’m really stuck :neutral_face:. Thank you

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4

In my case I’m using a LoadBalancer :thinking: . I found this thread with a large discussion and different members experiences where I think you could take a couple of ideas to try:

5

I was able to fix the issue by adding the MCP Server certificat to the n8n pod . I’ve created a comfigMap with the certificat and mount it in the pod file system. And loaded the extra certificate through the environment variable NODE_EXTRA_CA_CERTS

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6

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