Flux API error: the validation failures specific to this model

Most API errors are the same on every model. These are the ones specific to Flux Pro v1.1 — payloads another model would accept.

What you sent	You get	Why
aspect_ratio outside 16:9, 9:16, 1:1, 4:3, 3:4	400 INVALID_PARAM	The widest set on the platform
n above 4	400 INVALID_PARAM	Batch cap, not a cost limit
model misspelled	400 UNKNOWN_MODEL	The exact id is flux-pro

All of these fail before anything is submitted upstream, so no credits are touched and there is nothing to reconcile. The response names the offending field in error.param.

The errors that are not your fault

Different category, and they arrive differently: a job that was accepted and then failed returns a successful HTTP response describing a failure.

{ "state": "failed", "error": { "code": "UPSTREAM_EMPTY_RESULT" } }

Your try/catch will not see it. Check state, not the status code. Credits refund in full. Full taxonomy in job state failed and UPSTREAM_FAIL.

Errors that apply to every model

• MISSING_API_KEY and INVALID_API_KEY
• NOT_ENOUGH_CREDITS
• api rate limit exceeded and CONCURRENCY_LIMIT_EXCEEDED
• INVALID_JSON

Full parameter reference: Flux API parameters.

Models covered on this page

• FLUX Pro