When wiring ChatGPT, Claude, or Gemini into a third-party client or bot plugin, the most common point of failure is an API key error: you clearly copied and pasted it, yet it still says invalid key, 401, unauthorized. The checklist below basically saves me every time.
Don’t rush to reinstall: 5 high-frequency causes
1 The copied key includes spaces or line breaks
Especially when copying from a webpage into a config file—one extra trailing space is enough to make you question your life. The most worry-free approach is to retype the key manually.
2 Put in the wrong place: environment variables not taking effect
Many tools support both a “config file” and “environment variables,” and you end up editing A while it reads B. It’s recommended to search the logs for key from or check the plugin documentation for the read priority order.
3 Wrong provider or model name selected
In multi-model clients it’s easy to use an OpenAI model name to call Claude, and the error can look quite similar. Don’t rely on memory for model lists—copy from the console for the most reliable result.
4 Permissions or quota issues
Some keys don’t have billing enabled by default / don’t have a card linked / don’t have the corresponding API permissions enabled, and then they get treated as “invalid.” Checking Usage and Billing in the console beats staring at error messages.
