Issue: Unable to connect to the SSE MCP server.

[acn-masatadakurihara]

App Version

3.19.2

API Provider

VS Code Language Model API

Model Used

GPT4.1

🔁 Steps to Reproduce

1. Start the SSE server
2. Check the MCP settings in Roo Code

💥 Outcome Summary

It seems that since version 3.19.2, it is no longer possible to connect to the SSE MCP.
Perhaps the following change is the cause?

Add support for Streamable HTTP Transport MCP servers (thanks @taylorwilsdon!)

3.19.2

3.19.1

📄 Relevant Logs or Errors (Optional)

[dosubot]

Hi @acn-masatadakurihara! I'm Dosu and I’m helping the Roo-Code team.

I was unable to find any documentation or discussions that specifically address the change "Add support for Streamable HTTP Transport MCP servers" in version 3.19.2 or its impact on SSE MCP server connections. The available documentation covers general information about SSE transport and MCP server configuration, but does not mention this particular update or provide troubleshooting steps for the connection issue you described in 3.19.2. If you have access to more detailed logs or error messages, sharing those may help narrow down the cause. At this time, there is a gap in the official documentation regarding this specific version change and its effects on SSE MCP connectivity.

To reply, just mention my name @dosu.

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[chodak166]

Same here, also tried with "type": "sse". Downgrading to 3.19.1 works. Using supergateway like this:

{
  "mcpServers": {
    "fetch": {
      "type": "sse",
      "url": "http://localhost:8001/sse"
    },
    "google-search": {
      "url": "http://localhost:8002/sse"
    },
    "telegram": {
      "url": "http://localhost:8003/sse"
    },
    "context7": {
      "url": "http://localhost:8004/sse"
    }
  }
}

[taylorwilsdon]

Ack - hm, nothing should have changed about SSE at all in #4210

I thought I had all 3 types going in the validator test config but I can reproduce with cloudflare's doc SSE endpoint. One sec - PR incoming

[taylorwilsdon]

[taylorwilsdon]

OK - fix is live in #4251
Thanks!