[MCP][filesystem] InternalServerError: stream is not readable

[luebken]

What happened?

When running the filesystem MCP server from examples, it fails to connect with the following error:

2025-03-24 21:46:54 error: [MCP][filesystem] Initialization failed Error POSTing to endpoint (HTTP 400): InternalServerError: stream is not readable

Version Information

git rev-parse HEAD
1d29c1e

Steps to Reproduce

1: Add a new script call to packages/mcp/package.json:

"start:filesystem-sse": "node -r dotenv/config --loader ./tsconfig-paths-bootstrap.mjs --experimental-specifier-resolution=node ./src/examples/filesystem.ts --transport=sse .",`

2: Start the filesytem MCP server

$ cd packages/mcp; npm run start:filesystem-sse

> [email protected] start:filesystem-sse
> node -r dotenv/config --loader ./tsconfig-paths-bootstrap.mjs --experimental-specifier-resolution=node ./src/examples/filesystem.ts --transport=sse .

(node:23820) ExperimentalWarning: `--experimental-loader` may be removed in the future; instead use `register()`:
--import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register("./tsconfig-paths-bootstrap.mjs", pathToFileURL("./"));'
(Use `node --trace-warnings ...` to show where the warning was created)
(node:23820) [DEP0180] DeprecationWarning: fs.Stats constructor is deprecated.
(Use `node --trace-deprecation ...` to show where the warning was created)
Secure MCP Filesystem Server running on SSE at http://localhost:3001/sse
Allowed directories: [ '/users/mdl/workspace/other/librechat/packages/mcp' ]

3: Configure the MCP server in librechat.yaml

mcpServers:
  filesystem:
    url: http://localhost:3001/sse
    timeout: 60000

4: Run the backend:

$ npm run backend
...
2025-03-24 21:55:32 info: [MCP] Initializing servers
2025-03-24 21:55:32 info: [MCP][filesystem] Connection state: connecting
2025-03-24 21:55:32 info: [MCP][filesystem] Creating SSE transport: http://localhost:3001/sse
2025-03-24 21:55:32 info: [MCP][filesystem] Connection state: error
2025-03-24 21:55:32 error: [MCP][filesystem] Connection failed: Error POSTing to endpoint (HTTP 400): InternalServerError: stream is not readable
2025-03-24 21:55:34 info: [MCP][filesystem] Connection state: disconnected
...

What browsers are you seeing the problem on?

No response

Relevant log output

Screenshots

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