Model error diagnosis

OpenAI: GPT-5.3-Codex | model capability unsupported

OpenAI: GPT-5.3-Codex returning 400 / model capability unsupported means you should first confirm whether model ID openai/gpt-5.3-codex is visible for this OpenAI key, then separate permission, context, capability, rate limit, or route issues.

Model

openai/gpt-5.3-codex

OpenAI: GPT-5.3-Codex

Provider

OpenAI

62 models in catalog

Error type

model capability unsupported

capability-unsupported

Status code

400

global model route

Model error summary

Model

openai/gpt-5.3-codex

Error type

capability-unsupported

Status code

400

Read-only check. Detection data burns after 5 minutes.

What this model error usually means

OpenAI: GPT-5.3-Codex returning 400 / model capability unsupported means you should first confirm whether model ID openai/gpt-5.3-codex is visible for this OpenAI key, then separate permission, context, capability, rate limit, or route issues.

Model: openai/gpt-5.3-codex
Provider: OpenAI
Status code: 400

How to prove it during checking

Read-only check. Detection data burns after 5 minutes.

List models: confirm whether openai/gpt-5.3-codex is actually visible instead of guessing from the display name.
Light probe: use minimal input to verify whether OpenAI returns the same 400, then record the error body.
Compare model facts: context 400,000, input $1.75, output $14.
supports include_reasoning
supports max_completion_tokens
supports max_tokens
supports reasoning

Next action

OpenAI: GPT-5.3-Codex model capability unsupported should not end at failed. Return the next move: change model ID, add permission, reduce context, disable unsupported capability, change route, monitor, or hold listing.

Context: 400,000
Price: $1.75 / $14
Read-only check. Detection data burns after 5 minutes.

Open key checker

Read-only check. Detection data burns after 5 minutes.

Open models

OpenAI: GPT-5.3-Codex

Open providers

OpenAI