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PostgreSQL MCP client error: self-signed certificate with sslmode on #1803
Description
Describe the bug
Using postgresql with SSLmode active in DB (alloydb gcp) in n8n self-hosted
To Reproduce
In n8n
- Add MCP client - execute tools
- Config credentials +
- STDIO
- Command npx
5.-y @modelcontextprotocol/server-postgres postgresql://user@password@google-db:5432/mydb?sslmode=require - Save
And use in agentAI, generate:
Failed execute operation: Failed to execute tool ‘query’: MCP error -32603: self-signed certicate
But, if we use postgresql n8n native node with this parameters, it works ok.
Expected behavior
Connect and operate correct in postgresql db with queries with sslmode true (require)
Logs
NA
Additional context
If we use postgresql db without sslmode active, or postgresql db bitnami default (localhost), the MCP client works ok.
Thanks!
Activity
[-]PostgreSQL MCP client error: self-signed certificate[/-][+]PostgreSQL MCP client error: self-signed certificate whit sslmode on[/+][-]PostgreSQL MCP client error: self-signed certificate whit sslmode on[/-][+]PostgreSQL MCP client error: self-signed certificate with sslmode on[/+]Connoropolous commentedon May 17, 2025
Hit this today. Got over it.
In order for it to work, you need to include the "CA Cert" for it... it will be available from the provider, maybe google in your case?
Download it, put it somewhere in your file system, and then append this to your DB string after sslmode=require
&sslrootcert=/path/to/your/cert/ca-certificate.crt
I have a feeling it's not a bug so much as legit security practices
wfrankoti commentedon May 21, 2025
Thank you @Connoropolous for your answer.
My point is that using the n8n native PostgreSQL node, you don't need to pass the certificate, and it works correctly. Why is it required (in the connection string) when using the MCP server with PostgreSQL?
olaservo commentedon May 29, 2025
Thanks for reporting this. This server has been moved to the archived repository at https://github.com/modelcontextprotocol/servers-archived to reduce maintenance overhead, so we can focus our efforts on a smaller set of core servers.
Since this server is no longer actively maintained, we recommend checking out the alternatives listed in the Readme.