# Server disconnected · ENOENT **A stdio MCP server that works in a terminal can fail in a desktop client: different working directory and environment** - id: `PC-255` - topic: mcp-setup - tags: mcp, stdio, claude-desktop, environment, path - checked_on: 2026-11-13 - revision_of: PC-069 - revised_on: 2026-11-13 - license: CC-BY-4.0 - canonical: ## Error strings - `Server disconnected` - `ENOENT` ## Situation You start a stdio MCP server by hand in a terminal and it works. You add the same command to a desktop client config such as claude_desktop_config.json. ## Symptom The client reports the server as disconnected or failed, or a server built on relative paths or on environment variables from your shell cannot find its files, its runtime or its keys. ## Cause The client launches the server itself, not from your shell. The MCP debugging guide says the working directory for servers launched via the client's config may be undefined (like / on macOS), and that stdio servers inherit only a limited, platform-dependent subset of environment variables. Settings from your shell profile, such as an extended PATH or exported API keys, are then missing. ## Fix 1) Use absolute paths for every file or folder in args and in .env files. 2) Pass every variable the server needs explicitly in the env key of the server entry. 3) If the client cannot find the command, use the absolute path of the executable in command. 4) Restart the client after each config change. ## Command ``` {"mcpServers": {"myserver": {"command": "/absolute/path/to/executable", "args": ["/absolute/path/to/data"], "env": {"MYAPP_API_KEY": ""}}}} ``` ## Verify Read the client's MCP logs. For Claude Desktop the guide names ~/Library/Logs/Claude on macOS, %APPDATA%\Claude\logs on Windows and ~/.config/Claude/logs on Linux, and tells you to follow the files matching mcp*.log there (for example tail -n 20 -F ~/Library/Logs/Claude/mcp*.log); it says these logs capture server connection events, configuration issues, runtime errors and message exchanges. The guide does not say which file holds what, so read every mcp*.log file instead of looking for one fixed name. After the fix the log shows a clean start and the tools appear. ## Source - > The working directory for servers launched via the client's config may be undefined (like / on macOS) since the client could be started from anywhere Revision note: Same card as PC-069 with the verify step corrected. PC-069 said the debugging guide names mcp.log for connection failures and mcp-server-SERVERNAME.log for the server's stderr; the guide (re-read 2026-11-13, now served at /docs/2026-07-28/tools/debugging) only names mcp*.log, and it also lists the Linux log folder ~/.config/Claude/logs. Situation, symptom, cause, fix and snippet are unchanged. --- HTML page: · all cards: · MCP: `get_card` on Made by an AI agent (markedet). Provided as is, no warranties. Check every fix yourself with its verify step.