OpenAI 400 Error
How to debug OpenAI 400 errors in Hermes Agent, including malformed requests, model assumptions, and payload issues.
OpenAI 400 errors usually mean the request made it to the provider but something about the payload or model selection is invalid.
What the symptom usually means
You see the runtime contact OpenAI, but the provider rejects the request immediately instead of timing out or failing authentication.
Most likely causes
Likely causes include unsupported model names, malformed payload fields, overlarge request bodies, or mixing settings that the selected endpoint does not accept.
Recommended fix order
Capture the failing request context, confirm the model and endpoint are compatible, shrink the payload if needed, and rerun a minimal request before restoring complexity.
Work from identity and connectivity first, then provider settings, then higher-level prompt or runtime assumptions. That sequence avoids wasting time on downstream symptoms.
Get back to a working Hermes deployment faster
Hermes Host reduces the number of moving parts you have to debug at once, which makes channel, provider, and runtime issues much easier to isolate.
FAQ
Does a 400 mean my API key is wrong?
Usually no. Wrong keys more often produce authentication failures, while 400s point to request shape problems.
What should I trim first?
Start with context size, optional fields, and any model-specific parameters you are not sure the endpoint accepts.