Fails to connect to Zapier Mcp server

[sterankin]

What happened?

I setup a simple MCP Server on Zapier as part of their new offering and i added the url to the librechat.yaml under everything, errors on startup:

{"event":{},"level":"error","message":"[MCP][everything] Connection failed: SSE error: undefined","stack":"Error: SSE error: undefined\n    at _eventSource.onerror (file:///app/packages/mcp/dist/index.es.js:1:88138)\n    at EventSource.scheduleReconnect_fn (file:///app/node_modules/eventsource/dist/index.js:192:53)\n    at file:///app/node_modules/eventsource/dist/index.js:45:174\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"}
{"event":{},"level":"error","message":"[MCP][everything] Connection failed: SSE error: undefined","stack":"Error: SSE error: undefined\n    at _eventSource.onerror (file:///app/packages/mcp/dist/index.es.js:1:88138)\n    at EventSource.scheduleReconnect_fn (file:///app/node_modules/eventsource/dist/index.js:192:53)\n    at file:///app/node_modules/eventsource/dist/index.js:45:174\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"}
{"event":{},"level":"error","message":"[MCP][everything] Connection failed: SSE error: undefined","stack":"Error: SSE error: undefined\n    at _eventSource.onerror (file:///app/packages/mcp/dist/index.es.js:1:88138)\n    at EventSource.scheduleReconnect_fn (file:///app/node_modules/eventsource/dist/index.js:192:53)\n    at file:///app/node_modules/eventsource/dist/index.js:45:174\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"}
{"level":"error","message":"[MCP][everything] Failed after 3 attempts"}
{"event":{},"level":"error","message":"[MCP][everything] Initialization failed SSE error: undefined","stack":"Error: SSE error: undefined\n    at _eventSource.onerror (file:///app/packages/mcp/dist/index.es.js:1:88138)\n    at EventSource.scheduleReconnect_fn (file:///app/node_modules/eventsource/dist/index.js:192:53)\n    at file:///app/node_modules/eventsource/dist/index.js:45:174\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"}
{"level":"error","message":"[MCP] No servers initialized"}

debug log:

2025-03-23T16:44:19.072Z info: [MCP][everything] Connection state: error
2025-03-23T16:44:19.073Z error: [MCP][everything] Connection failed: SSE error: undefined
2025-03-23T16:44:23.080Z info: [MCP][everything] Connection state: disconnected
2025-03-23T16:44:23.081Z info: [MCP][everything] Connection state: connecting
2025-03-23T16:44:23.081Z info: [MCP][everything] Creating SSE transport: https://actions.zapier.com/mcp/REDACTED/sse
2025-03-23T16:44:23.238Z info: [MCP][everything] Connection state: error
2025-03-23T16:44:23.240Z error: [MCP][everything] Connection failed: SSE error: undefined
2025-03-23T16:44:23.241Z error: [MCP][everything] Failed after 3 attempts
2025-03-23T16:44:23.242Z error: [MCP][everything] Initialization failed SSE error: undefined
2025-03-23T16:44:23.242Z info: [MCP] Initialized 0/1 server(s)
2025-03-23T16:44:23.242Z warn: [MCP] 1/1 server(s) failed to initialize
2025-03-23T16:44:23.243Z info: [MCP][everything] ✗ Failed
2025-03-23T16:44:23.244Z error: [MCP] No servers initialized

It the Zapier endpoint works fine when I connect to it in a terminal in a simple python script and I am able to interact with the tools using the anthropic client example, so there is something in LibreChat which is causing an issue.

    async def connect_to_server(self, server_url: str):
        """
        Connect to an MCP server via SSE.
        
        Args:
            server_url: URL of the MCP server SSE endpoint (e.g., "http://localhost:8000/")
        """
        print(f"Connecting to SSE MCP server at {server_url}")
        # Use the SSE client helper to connect.
        # This returns a tuple (read_stream, write_stream)
        streams = await self.exit_stack.enter_async_context(sse_client(server_url))
        self.session = await self.exit_stack.enter_async_context(ClientSession(streams[0], streams[1]))
        await self.session.initialize()
        
        # List available tools
        response = await self.session.list_tools()
        tools = response.tools
        print("\nConnected to server with tools:", [tool.name for tool in tools])
        return tools

Version Information

ghcr.io/danny-avila/librechat-dev latest 7c6d45a52fb0 3 days ago 1.57GB
ghcr.io/danny-avila/librechat-rag-api-dev-lite latest f96c21d7fc2f 2 weeks ago 1.79GB

Running latest

Steps to Reproduce

Setup a simple Zapier mcp server, copy the url generated and add to yaml in librechat, start the docker conteiner.

What browsers are you seeing the problem on?

No response

Relevant log output

Screenshots

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[danny-avila]

I will try it myself later but looking at your link, you should remove the /sse part in the URL you set in the config.

From looking at this part: [MCP][everything] Creating SSE transport: https://actions.zapier.com/mcp/REDACTED/sse

I also recommend renaming "everything" from the example.

on that note, please share the relevant part of your librechat.yaml config to better troubleshoot, with sensitive values redacted

[sterankin]

Thanks danny, I removed the sse part and still shows this in the logs after restarting the docker container:

{"event":{},"level":"error","message":"[MCP][zapier] Connection failed: SSE error: undefined","stack":"Error: SSE error: undefined\n    at _eventSource.onerror (file:///app/packages/mcp/dist/index.es.js:1:88138)\n    at EventSource.scheduleReconnect_fn (file:///app/node_modules/eventsource/dist/index.js:192:53)\n    at file:///app/node_modules/eventsource/dist/index.js:45:174\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"}

2025-03-23T17:17:51.658Z info: [MCP][zapier] Creating SSE transport: https://actions.zapier.com/mcp/REDACTED
2025-03-23T17:17:51.840Z info: [MCP][zapier] Connection state: error
2025-03-23T17:17:51.841Z error: [MCP][zapier] Connection failed: SSE error: undefined
2025-03-23T17:17:51.842Z error: [MCP][zapier] Failed after 3 attempts

Librechat.yaml mcp section:

# Example MCP Servers Object Structure
mcpServers:
  zapier:
    url: https://actions.zapier.com/mcp/REDACTED
    timeout: 60000  # 1 minute timeout for this server, this is the default timeout for MCP servers.  

[danny-avila]

Actually with the full URL, including /sse it worked for me:

2025-03-23T17:38:37.473Z debug: [MCP][zapier] Transport sending: {"method":"notifications/initialized","jsonrpc":"2.0"}
|2025-03-23T17:38:37.532Z info: [MCP][zapier] Connection state: connected
2025-03-23T17:38:37.533Z info: [MCP][zapier] Capabilities: {"prompts":{"supported":false},"resources":{"supported":false},"tools":{"supported":true,"version":"2024-11-05"},"utilitie... [truncated]

my config:

mcpServers:
  zapier:
    url: https://actions.zapier.com/mcp/sk-SECRET/sse

Make sure you have actions configured, and that your LC instance has network access

[sterankin]

Thanks for checking. I have another MCP server (not Zapier, its a self hosted one) and its working ok (so not network issue). I keep getting the error on Zapier - it only occurs in LC. The Zapier MCP works fine when I run it with my own client python script.

So there is something specifically about my LC setup or docker but I am using a fresh download of the LC project. I can't explain it.

[danny-avila]

Make sure you are on the latest version, the Zapier MCP is working for me as commented above.

Updating Instructions (docker):

# Linux command to Remove all existing images
docker images -a | grep "librechat" | awk '{print $3}' | xargs docker rmi

# Windows Powershell
docker images -a | findstr "librechat" | ForEach-Object { docker rmi $_.Split()[2] }

Then follow the directions here: https://www.librechat.ai/docs/local/docker#update-librechat

[sterankin]

Thanks for those instructions.
I deleted all docker images, did a git pull and a docker compose pull. Then docker compose up.

Still getting the same error.

{"event":{},"level":"error","message":"[MCP][zapier] Initialization failed SSE error: undefined","stack":"Error: SSE error: undefined\n at _eventSource.onerror (file:///app/packages/mcp/dist/index.es.js:1:88218)\n at EventSource.scheduleReconnect_fn (file:///app/node_modules/eventsource/dist/index.js:192:53)\n at file:///app/node_modules/eventsource/dist/index.js:45:174\n at process.processTicksAndRejections (node:internal/process/task_queues:95:5)"}

If I put the Zapier url into my browser it works fine. Likewise in my python local script which runs in the terminal (basically the anthropic mcp client example) it all works ok. I just can't seem to get it to work from LC.

I am in a company network so there may be restrictions - but the fact it works from the python terminal app would indicate otherwise.
But is there a way to add a custom cert to the docker image (for Zscaler for example)

[sterankin]

I downloaded the Zscaler cert and added it to the base dockerfile:

# Base node image
FROM node:20-alpine AS node

COPY ZscalerRootCertificate-2048-SHA256.crt /usr/local/share/ca-certificates/ZscalerRootCertificate-2048-SHA256.crt
RUN apk --no-cache add --no-check-certificate ca-certificates \
    && update-ca-certificates

I then used the override docker compose to use the local build:

services:

# # USE LIBRECHAT CONFIG FILE
#   api:
#     volumes:
#     - type: bind
#       source: ./librechat.yaml
#       target: /app/librechat.yaml

# LOCAL BUILD
  api:
    image: librechat
    build:
      context: .
      target: node

I removed all the older images and did a fresh docker compose up. Everything starts except LC which crashes and restarts constantly with exitcode 127

> [email protected] backend
> cross-env NODE_ENV=production node api/server/index.js

sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found
sh: cross-env: not found

> [email protected] backend
> cross-env NODE_ENV=production node api/server/index.js

sh: cross-env: not found

[danny-avila]

With a local build, make sure your project files are up to date, you need to make sure to git pull and check the latest commit with git log

Also docker compose build --no-cache helps

[danny-avila]

FWIW it's also working for me using docker:

LibreChat         | 2025-03-23T21:45:17.757Z info: [MCP][zapier] Available tools: google_calendar_find_event, edit_actions, add_actions

[sterankin]

Thanks for all the help and confirmations which helped me track down to the fact its a Zscaler issue and needed to get the cert inside the docker container.

Of course since alpine was used then update-ca-certificates is not available (and can;t be downloaded during build because of the aforementioned Zscaler)

Had to resort to using the node slim docker image which allowed me to get the cert installed ok.

Its now showing the tools from Zapier!