topic Re: Can't connect to custom MCP Server in Generative AI

Can't connect to custom MCP Server

smferro54epam — Thu, 30 Oct 2025 03:54:51 GMT

I've tried connecting from local environment, notebook and following the sample notebook here:
https://docs.databricks.com/aws/en/generative-ai/mcp/custom-mcp?language=Local+environment

And I'm always getting the same error:
httpx.ConnectError: All connection attempts failed

My mcp server was deployed correctly, authentication for the service principal is fine, I'm not sure about the networking, I understand private connectivity was enabled but do not understand how it may affect the deployment.

Re: Can't connect to custom MCP Server

Thompson2345 — Thu, 30 Oct 2025 06:33:21 GMT

The httpx.ConnectError usually indicates a network connectivity issue rather than authentication. Since you enabled private connectivity, your MCP server is likely only accessible within the VPC or through a configured private endpoint. From a local notebook or environment outside that network, the connection will fail. To fix this, either:

Use a notebook or compute instance within the same VPC or subnet.
Configure a secure VPN or bastion host to access the private endpoint.
If public access is acceptable, adjust the MCP deployment to allow public connectivity temporarily for testing.
Check the MCP docs on private connectivity and endpoints — the error is consistent with trying to reach a private-only service from outside its network.”

I can also draft a simpler, one-paragraph version for quick forum posting if you want.

Re: Can't connect to custom MCP Server

smferro54epam — Thu, 30 Oct 2025 12:28:18 GMT

will try and come back if solved, thanks @Thompson2345 !

Re: Can't connect to custom MCP Server

CharlotteMarti2 — Fri, 31 Oct 2025 08:32:08 GMT

Check your network settings and firewall rules — the error means your environment can’t reach the MCP server. Make sure the server’s endpoint is accessible from your workspace and that private connectivity or VPC settings allow outbound traffic to it.

Re: Can't connect to custom MCP Server

smferro54epam — Mon, 03 Nov 2025 16:38:05 GMT

I wasn't setting the MCP server as a streamable http, I've done that already and it works!