What happened?
I have access to the new gpt-5.6 model in ChatGPT on other surfaces, including iOS and Windows, but Codex CLI does not appear to support it when using ChatGPT authentication.
The CLI is current according to codex update, but a direct model probe fails with a 400 response:
ERROR: {"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.6' model is not supported when using Codex with a ChatGPT account."}}
This makes it look like model availability is inconsistent between ChatGPT app surfaces and Codex CLI, or that the CLI does not surface the reason/rollout state clearly.
Steps to reproduce
- Use Codex CLI with ChatGPT auth.
- Confirm the CLI is current:
Observed update result:
Resolved version: 0.144.1
Codex CLI 0.144.1 installed successfully.
- Try to run Codex with
gpt-5.6:
codex exec --skip-git-repo-check --ephemeral -m gpt-5.6 --sandbox read-only "Reply with exactly: model-ok"
Expected behavior
If gpt-5.6 is available to the same ChatGPT account in ChatGPT apps, Codex CLI should either:
- allow
gpt-5.6 when launched with -m gpt-5.6, or
- clearly explain that Codex has a separate model availability policy/rollout from ChatGPT app surfaces and show which models are currently supported for Codex with ChatGPT auth.
Actual behavior
The CLI starts with the requested model, warns that metadata is missing, then fails:
OpenAI Codex v0.144.1
model: gpt-5.6
provider: openai
approval: on-request
sandbox: read-only
reasoning effort: high
warning: Model metadata for `gpt-5.6` not found. Defaulting to fallback metadata; this can degrade performance and cause issues.
ERROR: {"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.6' model is not supported when using Codex with a ChatGPT account."}}
Environment
Codex CLI: 0.144.1
Platform: Linux x86_64
Auth mode: ChatGPT account
Configured model before test: gpt-5.5
codex doctor also reports:
Configuration: model gpt-5.5 · openai
Auth: stored auth mode chatgpt
Updates: cached latest version 0.144.1
Additional context
This may be intentional if Codex model availability lags or differs from ChatGPT app model availability, but the current behavior is confusing because there is no obvious app update available and the CLI updater reports the install is current.
What happened?
I have access to the new
gpt-5.6model in ChatGPT on other surfaces, including iOS and Windows, but Codex CLI does not appear to support it when using ChatGPT authentication.The CLI is current according to
codex update, but a direct model probe fails with a 400 response:This makes it look like model availability is inconsistent between ChatGPT app surfaces and Codex CLI, or that the CLI does not surface the reason/rollout state clearly.
Steps to reproduce
Observed update result:
gpt-5.6:Expected behavior
If
gpt-5.6is available to the same ChatGPT account in ChatGPT apps, Codex CLI should either:gpt-5.6when launched with-m gpt-5.6, orActual behavior
The CLI starts with the requested model, warns that metadata is missing, then fails:
Environment
codex doctoralso reports:Additional context
This may be intentional if Codex model availability lags or differs from ChatGPT app model availability, but the current behavior is confusing because there is no obvious app update available and the CLI updater reports the install is current.