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Bad request errors across LLM providers
How bad request errors show up across Gemini, OpenAI, Anthropic, OpenRouter and more, and how to route around them.
A 400 means the provider rejected the request shape itself — a parameter out of range, a malformed tool call, or a field one API version accepts and another rejects. These are deterministic: the same request fails the same way every time, so retries without a change are wasted spend. Fix the payload, or let Autofix patch and resend it in flight.
| Code | Error | Affected teams / 30 days | |
|---|---|---|---|
| 400 |  DeepSeek 400 — reasoning_content must be passed |
48 | View |
| 400 |  Gemini 400 — Function call missing a thought_signature |
42 | View |
| 400 |  OpenAI 400 — Context length exceeded |
34 | View |
| 400 |  Anthropic 400 — You are out of extra usage |
30 | View |