This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite #31705

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1. luwei1990

   added

   appIssues related to the Codex desktop appIssues related to the Codex desktop app

   on Jul 9, 2026
2. github-actions

   added

   bugSomething isn't workingSomething isn't working

   CLIIssues related to the Codex CLIIssues related to the Codex CLI

   execIssues related to the `codex exec` subcommandIssues related to the `codex exec` subcommand

   on Jul 9, 2026
3. github-actions commented on Jul 9, 2026

   

   github-actionsBot

   on Jul 9, 2026 – with GitHub Actions

   Contributor

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   Potential duplicates detected. Please review them and close your issue if it is a duplicate.

   • gpt-5.5 on ChatGPT account is routed to Responses-Lite and fails with unsupported_value #31150
   • Regression: gpt-5.5 fails after Codex update with X-OpenAI-Internal-Codex-Responses-Lite #30403
   • Codex App: GPT-5.5 fails with X-OpenAI-Internal-Codex-Responses-Lite while GPT-5.4 works #30406
   • Bug: "Model not supported when using X-OpenAI-Internal-Codex-Responses-Lite" error with latest models #30461
   • This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite. #30912

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4. sunflower-zzn commented on Jul 23, 2026

   

   sunflower-zzn

   on Jul 23, 2026 – with ChatGPT Codex Connector

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   I can reproduce the same 400 unsupported_value error specifically in the automatic approval reviewer path.

   Environment:

   • Codex Desktop: 26.715.72359 (build 5718)
   • Bundled CLI: 0.145.0-alpha.30
   • Platform: macOS
   • Auth mode: ChatGPT
   • Main task model: gpt-5.6-sol

   Observed behavior:

   1. The main task runs normally.
   2. An action requiring approval triggers a separate reviewer task using model=codex-auto-review.
   3. The reviewer request fails before producing any tokens:

      400 unsupported_value
      This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite.
      param: model
      

   4. Codex then converts that reviewer infrastructure failure into:

      This action was rejected due to unacceptable risk.
      Reason: Automatic approval review failed: ...
      

   This is not a risk-policy denial: the reviewer model call itself fails. In one hour I observed 7 actual tool rejections across 4 task threads with the same signature.

   The current model catalog entry for codex-auto-review advertises use_responses_lite: true, while the backend rejects that model on the Lite route. This looks like a model metadata/routing mismatch.

   Expected behavior:

   • Do not route codex-auto-review through Responses Lite when unsupported, or retry through the full Responses path.
   • If the reviewer infrastructure fails with a 4xx/model compatibility error, fall back to manual user approval instead of reporting the action as unacceptable risk.

   Related auto-review failures: #31255 and #33085.
5. ss-farm-systems commented on Jul 23, 2026

   

   ss-farm-systems

   on Jul 23, 2026

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   Confirmed the Guardian-specific failure on macOS with Codex CLI 0.145.0 and ChatGPT auth.

   Observed on 2026-07-23:

   • The installed client's fresh remote catalog returned codex-auto-review as GPT-5.6-Terra with use_responses_lite=true.
   • The bundled catalog and current main both define codex-auto-review with use_responses_lite=false.
   • When an approval reached Guardian, the backend rejected the Lite request with 400 unsupported_value before Guardian produced a policy decision.

   I tested a narrow request-time guard on main at 44d76c6a6dd04fa2efc302b906ac8774267a1272:

   • Apply only when the session source is Guardian.
   • Apply only when the effective model slug is exactly the provider's default codex-auto-review.
   • If remote metadata says Lite, clone the request's ModelInfo and set use_responses_lite=false.
   • Leave explicit auto-review model overrides and ordinary Lite sessions unchanged.
   • Use the corrected request metadata consistently for HTTP, WebSocket, prewarm, and compaction. There is no retry, user-review fallback, or auto-approval.

   Validation:

   • 3 focused regression tests passed.
   • 32 related Auto-review and Responses-Lite tests passed.
   • just fix -p codex-core passed.
   • codex-cli built successfully.
   • Feeding the installed client's exact bad catalog into the patched binary emitted disabling Responses Lite for the default Guardian approval reviewer, returned a real Guardian declined decision, and completed the turn. There was no unsupported_value or Responses-Lite transport error.

   The declined outcome is important: policy remained fail-closed, but Guardian was able to evaluate the request instead of an infrastructure 400 being mislabeled as unacceptable risk.
6. etraut-openai commented on Oct 12, 2026

   

   etraut-openai

   on Oct 12, 2026

   Contributor

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   (response from codex)

   Closing the original gpt-5.5/Windows routing report as a duplicate of #31150. Both show gpt-5.4 working and gpt-5.5 rejected with the same Responses Lite unsupported-model error. Please keep the later Guardian-model observation distinct in #31150 or a targeted Guardian issue, since it need not have the same cause.
7. etraut-openai

   closed this as a duplicateof gpt-5.5 on ChatGPT account is routed to Responses-Lite and fails with unsupported_value #31150 on Oct 12, 2026