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Troubleshooting

Fix 401 Unauthorized and missing API key errors in MCP servers

Most MCP servers that connect to a service need an API key or token, passed as an environment variable in the config. A 401 means the key is missing, wrong or expired. Add it under "env" in the server config with the exact variable name from the README, then restart the app.

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Why it happens

  • The key was never added.
  • The variable name does not match what the server expects.
  • The key is expired or lacks the right permissions.

How to fix it

  1. 1

    Add the key to the config

    "my-server": {
  "command": "npx",
  "args": ["-y", "package-name"],
  "env": { "API_KEY": "your-key" }
}
  2. 2

    Match the variable name

    Copy the exact name from the server's README. Names are case-sensitive.

  3. 3

    Check the key itself

    Create a fresh key with the scopes the README lists, and never commit it to a shared repository.

Still stuck? Every server page on this site shows the exact config for each app. Find your server.