How to fix 'MCP server not found' error

The server not found error appears in different forms depending on the host and operating system. Check your MCP host's error display and server logs for the exact message. Each variant points to the same root cause — the command cannot be found — but knowing the exact message helps confirm the diagnosis. Check Claude Desktop logs at ~/Library/Logs/Claude/mcp*.log on macOS.

1# Common error messages you might see:
2
3# Node.js / npx errors:
4# "spawn npx ENOENT"
5# "Error: spawn npx ENOENT"
6# "command not found: npx"
7
8# General MCP errors:
9# "Error: MCP server not found"
10# "Failed to start MCP server"
11# "Server process exited with code 1"
12
13# Python / uvx errors:
14# "spawn uvx ENOENT"
15# "command not found: uvx"

GUI applications do not inherit your shell's PATH (set in .bashrc, .zshrc, or .config/fish/config.fish). This means npx, node, uvx, and python might not be findable. The fix is to use the absolute path. Open your terminal and run which or where to find it.

1# macOS / Linux — find absolute paths
2which node        # e.g., /opt/homebrew/bin/node
3which npx         # e.g., /opt/homebrew/bin/npx
4which uvx         # e.g., /Users/you/.local/bin/uvx
5which python3     # e.g., /opt/homebrew/bin/python3
6
7# Windows — find absolute paths
8where node        # e.g., C:\Program Files\nodejs\node.exe
9where npx         # e.g., C:\Program Files\nodejs\npx.cmd

Replace the command name in your MCP host config with the absolute path you found. This bypasses all PATH resolution and guarantees the host can find the binary. For npx-based servers, replace "npx" with the full path. For node-based servers, replace "node" with the full path.

1// BEFORE — relative command (fails in GUI apps)
2{
3  "mcpServers": {
4    "github": {
5      "command": "npx",
6      "args": ["-y", "@modelcontextprotocol/server-github"],
7      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_token" }
8    }
9  }
10}
11
12// AFTER — absolute path (works everywhere)
13{
14  "mcpServers": {
15    "github": {
16      "command": "/opt/homebrew/bin/npx",
17      "args": ["-y", "@modelcontextprotocol/server-github"],
18      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_token" }
19    }
20  }
21}

On Windows, even absolute paths to npx can fail because npx.cmd is a batch script, not a direct executable. The solution is to use cmd.exe as the command and pass /c npx as arguments. This launches a command shell that properly resolves and executes npx.

1// Windows fix — wrap npx with cmd
2{
3  "mcpServers": {
4    "github": {
5      "command": "cmd",
6      "args": ["/c", "npx", "-y", "@modelcontextprotocol/server-github"],
7      "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_token" }
8    }
9  }
10}
11
12// Alternative: use absolute path to node directly
13{
14  "mcpServers": {
15    "my-server": {
16      "command": "C:\\Program Files\\nodejs\\node.exe",
17      "args": ["C:\\Users\\you\\mcp-server\\dist\\index.js"]
18    }
19  }
20}

After updating the config, restart your MCP host completely. Claude Desktop requires quit and reopen. Cursor needs a window reload or full restart. Check that the server's tools now appear in the host interface. If they do not, check the logs again — the error may have changed to a different issue (like missing environment variables), which means the PATH problem is fixed and you are making progress. If you continue having trouble after trying all these fixes, the RapidDev team has debugged hundreds of MCP configurations and can help identify unusual issues.