modelcontextprotocol / modelcontextprotocol/csharp-sdk
Bad Request of "Missing Session Id" from a stateful MCP server
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Description
I used the MCP Client SDK and was trying to call a MCP server. With a test connection of calling the ListServerTools and got below response:
Response status code does not indicate success: 400 (Bad Request). Response body: {"jsonrpc":"2.0","id":"server-error","error":{"code":-32600,"message":"Bad Request: Missing session ID"}}
I have read the document here https://csharp.sdk.modelcontextprotocol.io/v1/concepts/stateless/stateless.html
In my understanding the client SDK should be able to handle the Mcp_Session_Id internally, or anything I have missed?
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the ListServerTools call with the MCP Client SDK against a stateful MCP server, using the reported 400 response as the baseline. Read the linked stateful/stateless documentation and trace how the client handles the Mcp_Session_Id. Done means the request succeeds with the required session handling, or the expected client configuration is clearly documented.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- csharp
- Domain
- api
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100