MCP Server spawn ENOENT — Fix for npx, uvx, and Node

Why spawn ENOENT happens

ENOENT is the Unix/POSIX error code for "No such file or directory". When you see spawn ENOENT in an MCP server log, it means the operating system's execvp call failed because the binary you specified does not exist at that path or on any directory in the process's PATH.

Claude Desktop launches MCP servers using child_process.spawn() in Node.js with a minimal inherited environment. On macOS and Linux, the PATH available to Claude Desktop typically contains only /usr/bin, /bin, and /usr/sbin. It does not contain:

• Homebrew paths (/usr/local/bin, /opt/homebrew/bin)
• nvm shim directories (~/.nvm/versions/node/vX/bin)
• pyenv paths (~/.pyenv/shims)
• uv/uvx paths (~/.local/bin)
• npm global bin (~/.npm/bin, ~/AppData/Roaming/npm on Windows)

So even though npx works in your terminal, Claude Desktop cannot find it.

Confirm this is your error

# macOS
tail -20 ~/Library/Logs/Claude/mcp-server-SERVERNAME.log

# Windows
Get-Content "$env:APPDATA\Claude\logs\mcp-server-SERVERNAME.log" -Tail 20

# Linux
tail -20 ~/.config/Claude/logs/mcp-server-SERVERNAME.log

You will see something like:

Error: spawn npx ENOENT
    at ChildProcess._handle.onexit (node:internal/child_process:285:19)
    at onErrorNT (node:internal/child_process:483:16)

Or on Windows:

Error: spawn uvx ENOENT
    at Process.ChildProcess._handle.onexit

Fix on macOS

# Find the absolute path to npx
which npx
# Intel Mac (system Node): /usr/local/bin/npx
# Apple Silicon (Homebrew): /opt/homebrew/bin/npx
# nvm: something like /Users/you/.nvm/versions/node/v20.0.0/bin/npx

# Find uvx if you use Python MCP servers
which uvx
# Usually: /Users/you/.local/bin/uvx

Update your config:

{
  "mcpServers": {
    "filesystem": {
      "command": "/opt/homebrew/bin/npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/you/projects"]
    },
    "git": {
      "command": "/Users/you/.local/bin/uvx",
      "args": ["mcp-server-git", "--repository", "/Users/you/myrepo"]
    }
  }
}

Fix on Windows

# PowerShell - find npx
where npx
# Typically: C:\Users\you\AppData\Roaming\npm\npx.cmd

# If multiple results, use the .cmd version

Update your config, using forward slashes and npx.cmd:

{
  "mcpServers": {
    "filesystem": {
      "command": "C:/Users/you/AppData/Roaming/npm/npx.cmd",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "C:/Users/you/projects"]
    }
  }
}

Fix on Linux

# Find paths
which npx    # e.g. /usr/local/bin/npx or /usr/bin/npx
which uvx    # e.g. /home/you/.local/bin/uvx
which node   # e.g. /usr/bin/node

If Node.js was installed via nvm, the path will look like: /home/you/.nvm/versions/node/v20.11.1/bin/npx. Use the full path from which npx.

uvx not found / spawn uvx ENOENT

If which uvx returns nothing, uv (the package manager that provides uvx) is not installed. Install it:

# macOS/Linux
curl -LsSf https://astral.sh/uv/install.sh | sh

# Windows (PowerShell)
powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

After installing, open a new terminal (the installer modifies your shell profile and the current session needs to reload it), then run which uvx again and use that absolute path in your config.

Preventing future spawn ENOENT errors

The pattern that causes this is fragile: the config depends on binaries installed at paths that could change. A more durable approach:

FAQ