Errors and fixes
The exact message, what causes it, and the change that fixes it. Search here before you paste a stack trace into a search engine.
- Universal
401 Unauthorized / Incorrect API key provided
The service did not accept your key. Usually it is a typo, a key from another project, a key that was revoked, or a variable that was never loaded.
- Universal
503 / 529 The service is overloaded, try again later
The provider is short of capacity right now. Your request was fine. Retry with a delay and have a fallback.
- Universal
404 The model does not exist or you do not have access to it
The model name is wrong, retired, or not enabled for your account or region.
- ChatGPTGemini
This model's maximum context length is N tokens
The request is longer than the model can hold. Your prompt, the whole conversation history and the space reserved for the answer all count. The…
Tested on GPT-5 · May 2026
- ChatGPT
429 Too Many Requests / Rate limit reached
You crossed a request or token limit for your tier. Backoff with jitter and batching fix it. A shorter sleep does not, and the response header tells…
Tested on GPT-5 · May 2026