MacOS Claude Desktop - 'Server transport closed unexpectedly, this is likely due to the process exiting early' error

[srustamo]

Describe the bug
MCP Server starts fine
Claude Desktop (the client) connects and sends an "initialize" message
Immediately after, the connection drops
Either Claude Desktop crashes / exits
Or the server crashes right after receiving the message
Server tries to write back → EPIPE error (because client connection is already closed)
Everything shuts down cleanly but prematurely
To Reproduce
Steps to reproduce the behavior:

1. Install MCP server with npm i @modelcontextprotocol/server-filesystem

Expected behavior
Claude Desktop connects to sever successfully.

Logs
2025-05-12T13:59:25.751Z [info] [filesystem] Initializing server...
2025-05-12T13:59:25.773Z [info] [filesystem] Server started and connected successfully
2025-05-12T13:59:25.783Z [info] [filesystem] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
2025-05-12T13:59:25.784Z [error] [filesystem] write EPIPE
2025-05-12T13:59:25.786Z [info] [filesystem] Server transport closed
2025-05-12T13:59:25.786Z [info] [filesystem] Client transport closed
2025-05-12T13:59:25.787Z [info] [filesystem] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-05-12T13:59:25.787Z [error] [filesystem] Server disconnected. For troubleshooting guidance, please visit our debugging documentation
2025-05-12T13:59:25.787Z [info] [filesystem] Client transport closed
2025-05-12T14:01:11.577Z [info] [filesystem] Initializing server...
2025-05-12T14:01:11.591Z [info] [filesystem] Server started and connected successfully
2025-05-12T14:01:11.596Z [info] [filesystem] Server transport closed
2025-05-12T14:01:11.596Z [info] [filesystem] Client transport closed
2025-05-12T14:01:11.596Z [info] [filesystem] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-05-12T14:01:11.596Z [error] [filesystem] Server disconnected. For troubleshooting guidance, please visit our debugging documentation
2025-05-12T14:01:11.597Z [info] [filesystem] Client transport closed

[garrettlove8]

I'm getting this error with a custom MCP server as well

[Ryanb58]

Also getting this error.

Runs as expected when done via terminal via the following commands.

npx -y @modelcontextprotocol/server-filesystem /Users/tbrazelton/Desktop /Users/tbrazelton/Downloads

npx -y @modelcontextprotocol/inspector npx @modelcontextprotocol/server-filesystem /Users/tbrazelton/Desktop /Users/tbrazelton/Downloads

I even tried giving claude desktop full disk access.

Running latest version of OSX on M1 Pro.

Logs:

2025-05-19T22:43:17.007Z [info] [filesystem] Initializing server...

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:43:17.007Z [filesystem] [info] Initializing server...
2025-05-19T22:43:17.064Z [filesystem] [info] Server started and connected successfully

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:43:17.064Z [info] [filesystem] Server started and connected successfully

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:43:17.067Z [filesystem] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:43:17.067Z [info] [filesystem] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
npx: installed 59 in 3.189s
Secure MCP Filesystem Server running on stdio
Allowed directories: [ '/Users/tbrazelton/Desktop', '/Users/tbrazelton/Downloads' ]
2025-05-19T22:44:17.066Z [filesystem] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:44:17.067Z [info] [filesystem] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:44:17.068Z [filesystem] [info] Client transport closed
2025-05-19T22:44:17.070Z [filesystem] [info] Server transport closed
2025-05-19T22:44:17.070Z [filesystem] [info] Client transport closed
2025-05-19T22:44:17.070Z [filesystem] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log.
2025-05-19T22:44:17.070Z [filesystem] [error] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging) {"context":"connection"}

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:44:17.068Z [info] [filesystem] Client transport closed
2025-05-19T22:44:17.070Z [info] [filesystem] Server transport closed
2025-05-19T22:44:17.070Z [info] [filesystem] Client transport closed
2025-05-19T22:44:17.070Z [info] [filesystem] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log.
2025-05-19T22:44:17.070Z [error] [filesystem] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging)

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:44:17.302Z [filesystem] [info] Server transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:44:17.303Z [info] [filesystem] Server transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:44:17.303Z [filesystem] [info] Client transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:44:17.303Z [info] [filesystem] Client transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:47:00.409Z [filesystem] [info] Initializing server...

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:47:00.409Z [info] [filesystem] Initializing server...

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:47:00.472Z [filesystem] [info] Server started and connected successfully

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:47:00.472Z [info] [filesystem] Server started and connected successfully

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:47:00.473Z [filesystem] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:47:00.473Z [info] [filesystem] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
npx: installed 59 in 2.819s
Secure MCP Filesystem Server running on stdio
Allowed directories: [ '/Users/tbrazelton/Documents/Blog Posts' ]
2025-05-19T22:48:00.475Z [filesystem] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}
2025-05-19T22:48:00.479Z [filesystem] [info] Client transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:48:00.478Z [info] [filesystem] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}
2025-05-19T22:48:00.479Z [info] [filesystem] Client transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:48:00.481Z [filesystem] [info] Server transport closed
2025-05-19T22:48:00.482Z [filesystem] [info] Client transport closed
2025-05-19T22:48:00.482Z [filesystem] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log.
2025-05-19T22:48:00.482Z [filesystem] [error] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging) {"context":"connection"}

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:48:00.482Z [info] [filesystem] Server transport closed
2025-05-19T22:48:00.482Z [info] [filesystem] Client transport closed
2025-05-19T22:48:00.482Z [info] [filesystem] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log.
2025-05-19T22:48:00.482Z [error] [filesystem] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging)

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:48:00.704Z [filesystem] [info] Server transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:48:00.704Z [info] [filesystem] Server transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:48:00.704Z [filesystem] [info] Client transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:48:00.704Z [info] [filesystem] Client transport closed

































ca
==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:51:02.060Z [filesystem] [info] Initializing server...

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:51:02.061Z [info] [filesystem] Initializing server...

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
2025-05-19T22:51:02.102Z [filesystem] [info] Server started and connected successfully
2025-05-19T22:51:02.103Z [filesystem] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:51:02.103Z [info] [filesystem] Server started and connected successfully
2025-05-19T22:51:02.103Z [info] [filesystem] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}

==> /Users/tbrazelton/Library/Logs/Claude/mcp-server-filesystem.log <==
command not found: /Users/tbrazelton/Desktop
2025-05-19T22:51:02.348Z [filesystem] [info] Server transport closed
2025-05-19T22:51:02.349Z [filesystem] [info] Client transport closed
2025-05-19T22:51:02.349Z [filesystem] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log.
2025-05-19T22:51:02.349Z [filesystem] [error] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging) {"context":"connection"}
2025-05-19T22:51:02.349Z [filesystem] [info] Client transport closed

==> /Users/tbrazelton/Library/Logs/Claude/mcp.log <==
2025-05-19T22:51:02.349Z [info] [filesystem] Server transport closed
2025-05-19T22:51:02.349Z [info] [filesystem] Client transport closed
2025-05-19T22:51:02.349Z [info] [filesystem] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log.
2025-05-19T22:51:02.349Z [error] [filesystem] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging)
2025-05-19T22:51:02.349Z [info] [filesystem] Client transport closed

Node Version:

➜  ~ node --version
v22.14.0
➜  ~ nvm --version
zsh: command not found: nvm
➜  ~ npm --version
10.9.2
➜  ~ 

[brodkin]

Same issue here. Running macOS Sequoia v15.5. Works fine in Docker, but only in Docker. Tested with Node v22 and v23

[paulchiu]

This fixed it for me #64 (comment)

TL;DR do nvm ls and do nvm uninstall [version] for anything older than 18. Restart Claude Desktop.

[katoro]

This fixed it for me #64 (comment)

TL;DR do nvm ls and do nvm uninstall [version] for anything older than 18. Restart Claude Desktop.

it works!

[sudokien]

I'm having the same issue on macOS Claude Desktop, using python command.

{
  "mcpServers": {
    "fetch": {
      "command": "python",
      "args": ["-m", "mcp_server_fetch"]
    }
}

Error log:

2025-06-07T10:10:44.177Z [fetch] [info] Initializing server... { metadata: undefined }
2025-06-07T10:10:44.197Z [fetch] [error] spawn python ENOENT {
  metadata: {
    context: 'connection',
    stack: 'Error: spawn python ENOENT\n' +
      '    at ChildProcess._handle.onexit (node:internal/child_process:285:19)\n' +
      '    at onErrorNT (node:internal/child_process:483:16)\n' +
      '    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)'
  }
}
2025-06-07T10:10:44.198Z [fetch] [error] spawn python ENOENT {
  metadata: {
    stack: 'Error: spawn python ENOENT\n' +
      '    at ChildProcess._handle.onexit (node:internal/child_process:285:19)\n' +
      '    at onErrorNT (node:internal/child_process:483:16)\n' +
      '    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)'
  }
}
2025-06-07T10:10:44.201Z [fetch] [info] Server transport closed { metadata: undefined }
2025-06-07T10:10:44.201Z [fetch] [info] Client transport closed { metadata: undefined }
2025-06-07T10:10:44.201Z [fetch] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log. { metadata: undefined }
2025-06-07T10:10:44.201Z [fetch] [error] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging) { metadata: { context: 'connection', stack: undefined } }

If I change the command from python to python3, I'll get this error log instead:

2025-06-07T10:14:44.333Z [fetch] [info] Initializing server... { metadata: undefined }
2025-06-07T10:14:44.379Z [fetch] [info] Server started and connected successfully { metadata: undefined }
2025-06-07T10:14:44.380Z [fetch] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0} { metadata: undefined }
/Library/Developer/CommandLineTools/usr/bin/python3: No module named mcp_server_fetch
2025-06-07T10:14:44.470Z [fetch] [info] Server transport closed { metadata: undefined }
2025-06-07T10:14:44.470Z [fetch] [info] Client transport closed { metadata: undefined }
2025-06-07T10:14:44.471Z [fetch] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log. { metadata: undefined }
2025-06-07T10:14:44.471Z [fetch] [error] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging) { metadata: { context: 'connection', stack: undefined } }
2025-06-07T10:14:44.471Z [fetch] [info] Client transport closed { metadata: undefined }

It seems like Claude Desktop is trying to use the Apple's system Python in /Library/Developer/CommandLineTools/usr/bin/python3. How to make it use my miniconda Python instead?

$ which python
/Users/myname/miniconda3/bin/python
$ python --version
Python 3.13.2
$ which python3
/Users/myname/miniconda3/bin/python3
$ python3 --version
Python 3.13.2

[Tylersuard]

Same issue! Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-07-04T06:50:03.173Z [error] [weather] Server disconnected. For troubleshooting guidance, please visit our debugging documentation
When I type nvm in my command line, it says "command not recognized". I am on Windows.

[sstklen]

Hey! I ran into a similar pattern in our bug knowledge base and thought this might help.

What's happening: Claude Desktop on macOS spawns MCP server processes without inheriting the user's shell PATH/environment. npx/node resolves to a different binary (or fails entirely) compared to your interactive terminal, causing the child process to exit immediately after spawn — hence EPIPE when the server tries to write back to the already-dead pipe.

What worked for us:

Use absolute paths for node/npx in your Claude Desktop MCP config, and explicitly set PATH in the env block. Run which npx and which node in your terminal to get the full paths, then update claude_desktop_config.json.

// ~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "filesystem": {
      "command": "/usr/local/bin/npx",  // or output of `which npx` e.g. /opt/homebrew/bin/npx
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/YOUR_USER/Desktop",
        "/Users/YOUR_USER/Downloads"
      ],
      "env": {
        "PATH": "/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin"
      }
    }
  }
}

Hope this helps! Let me know if it doesn't match your case — happy to dig deeper. 🦞

Disclosure: This analysis is from Confucius Debug, an AI-powered community KB for agent bugs. Please verify before applying.

---

_{🦞 Confucius Debug — community knowledge base for AI agent bugs. Free to search via MCP.}

[D1no]

Another option is simply to symlink to a known path so claude desktop (and other tools) stay happy. Using NVS (not NVM), but they also symlink through. Run the following for MacOS

Symlinks the default selected node, npm and npx command.

sudo ln -s $(which node) /usr/local/bin/node && ln -s $(which npx) /usr/local/bin/npx && ln -s $(which npm) /usr/local/bin/npm

[laozhangzzz]

This fits a common "works in terminal, fails in Claude Desktop" pattern.

If the same server command works manually but Claude Desktop reports Server transport closed unexpectedly / process exiting early / write EPIPE, the server package may be fine. The desktop app often launches stdio MCP servers without your interactive shell PATH, so node / npx from NVM, fnm, asdf, etc. is missing or resolves to the wrong version.

Things to verify:

• run which node && which npx in the terminal where it works
• use absolute paths in the MCP config instead of bare npx / node
• or use a wrapper script that exports the right Node bin path before exec npx ...
• fully quit/reopen Claude Desktop after editing config

Full checklist:
https://laozhangzzz.github.io/agent-pitbook/pits/mcp-stdio-server-exits-shell-path-not-inherited.html