Resolving the Codex Model Not Available Error

A Codex model is not available when your local client is outdated, your subscription tier has not received rollout access, or your enterprise administrator has kept the model disabled. At Layer3Labs, we build and run developer workflow automations, and missing model errors usually trace back to outdated local packages or staged account rollouts. Check the local software first.

A client that predates a model launch cannot list that identifier. For a full overview of what the tool does, see our OpenAI Codex guide. If you want GPT-6 Astra, your setup requires OpenAI Codex CLI version 0.153.1 or higher. New models also release gradually across ChatGPT surfaces.

Checking the Codex CLI Version First

The Codex CLI cannot request a model identifier that the software does not recognize. When OpenAI released GPT-6 Astra on September 3, 2026, support arrived in Codex CLI version 0.153.1. Run codex --version to check your build. Compare your output against releases on GitHub.

Updating your client resolves local recognition issues immediately. If the installed build is below 0.153.1, upgrade your package before editing configuration files. An outdated executable will fail even if your account has full access. Once the client is current, you can test whether the model is exposed to your user profile.

• codex --version: Prints the installed version of your terminal client.
• v0.153.1: The minimum CLI release required for gpt-6-astra recognition.
• September 3, 2026: The release date for the Astra model update.

Switching the Model in Configuration and the Terminal

Selecting a specific model in Codex requires using the exact model identifier. For GPT-6 Astra, that identifier is gpt-6-astra. You can set this value permanently in your configuration file or pass it as a flag during invocation. Codex reads configuration values from ~/.codex/config.toml.

In your configuration file, assign model = "gpt-6-astra" under your base settings. You can also specify model_provider = "openai" alongside your default reasoning parameters. Codex accepts five distinct reasoning-effort levels: low, medium, high, xhigh, and max. For complex debugging tasks, set model_reasoning_effort = "high" to allow deeper processing.

You do not need to rewrite your configuration file for a single test. The terminal client provides flags for interactive sessions and automated scripts.

• ~/.codex/config.toml: Set model = "gpt-6-astra" and model_reasoning_effort = "high" for permanent defaults.
• codex -m gpt-6-astra --reasoning-effort xhigh: Launches an interactive session overriding your configured model and reasoning level.
• codex exec --model gpt-6-astra: Runs non-interactive commands against the selected model without opening the terminal interface.
• /model gpt-6-astra: Changes the active model from within a running interactive terminal session.

Verifying Available Models for Your Account

Run codex models in your terminal. The command queries the OpenAI API to list every model your authenticated account can reach. If gpt-6-astra does not appear, your account lacks access. The Codex picker only displays models that your credentials can execute. A missing entry reflects an account entitlement restriction and points to access limits.

Account tiers dictate which users receive new model deployments. OpenAI announced the rollout of GPT-6 Pro, powered by GPT-6 Astra, on September 3, 2026. Access is rolling out to the ChatGPT Pro, Business, and Enterprise plans. Plus plans include GPT-6 Astra in ChatGPT Work and Codex as the staged release proceeds.

Plus subscribers often attempt to force access by purchasing extra usage credits. Credits do not bypass rollout waves. While Plus users can buy credits for more Work and Codex volume, buying credits does not grant early access during the rollout. You can verify your active subscription and project limits on the OpenAI platform. If your tier has not received the model, editing configuration files will produce authorization errors. Verify your tier before troubleshooting.

Enabling New Models in Enterprise Accounts

Enterprise accounts follow different deployment rules than individual subscriptions. In Enterprise workspaces, GPT-6 Astra is disabled by default upon release. Individual engineers cannot select the model until a workspace administrator enables it in the OpenAI admin console. If you belong to an Enterprise organization, your CLI will hide the model until your admin acts.

Administrators manage model availability directly inside workspace settings. To turn on access, the admin must navigate to the model management section of the administrative dashboard. OpenAI outlines model governance options in their ChatGPT model settings guide. Once an administrator turns on GPT-6 Astra, team members must run codex models again to refresh their local authorization cache.

• Default state: Enterprise workspaces keep new models turned off until administrators approve them.
• Admin console: Workspace owners enable gpt-6-astra in organizational policy controls.
• Local refresh: Running codex models confirms when organizational access filters down to your terminal.

Handling Discrepancies Across ChatGPT Work and Codex

Access to a newly released model does not activate simultaneously across all OpenAI interfaces. A single account can have GPT-6 Astra enabled in ChatGPT Work while the CLI continues to report the model as unavailable. OpenAI stages deployments across specific product surfaces. Seeing a model in your browser does not guarantee that your terminal client can reach it.

Discussions on the OpenAI community forum frequently show developers puzzled by these interface discrepancies. During a rollout the same login can be entitled in one surface and not another. If your account has Astra in Chat or Work, your Codex CLI access is likely queued for a subsequent wave. OpenAI has not published a fixed timeline for general availability, so waiting for rollout completion is necessary.

Do not re-authenticate repeatedly when you encounter this mismatch. Logging out and logging in will not force a surface entitlement to update ahead of schedule. Your account permissions will update automatically once the deployment wave reaches your profile.

Configuring Alternative Model Providers in Codex

Codex communicates using the standard OpenAI API protocol. Because the client relies on this protocol, routing requests to alternative model providers is a configuration setting. The model_provider key in ~/.codex/config.toml dictates where the client sends requests. Changing this value lets you target any service that implements a compatible API schema.

Developers often ask whether Codex supports Anthropic Claude or Google Gemini models natively. Codex does not bundle direct connectors for competing proprietary APIs. To use non-OpenAI architectures, the relevant setting is model_provider, because Codex speaks the OpenAI API protocol. Set model_provider and your custom endpoint in the configuration file.

When pointing Codex to third-party endpoints, verify your error handling. Standard API error codes are documented in the OpenAI API error guide. Compatibility issues typically arise when an alternative provider does not support reasoning parameters such as --reasoning-effort. Test endpoints with basic completion commands first.

Ordered Triage Sequence for Missing Models

The failure mode we hit most often is engineers modifying their configuration files before checking account permissions. Teams assume a local configuration change can force an unreleased model to respond. In practice, editing settings files on an account that lacks access produces authorization errors that look like software bugs. Check your account entitlements before touching local configuration files.

Following a disciplined three-step triage sequence prevents wasted debugging effort. Address the checks in this exact order to isolate the root cause.

If your version is current and your account is eligible, check for retired models. OpenAI maintains a list of retired endpoints in their deprecation documentation. Older model names will return availability errors as they phase out.

• 1. Check client version: Run codex --version to confirm your CLI is at v0.153.1 or higher.
• 2. Check account entitlements: Run codex models to verify whether your account tier currently exposes gpt-6-astra.
• 3. Check workspace and config: Confirm with your Enterprise administrator that the model toggle is enabled, then update ~/.codex/config.toml.

Audience Scope and What Flips This Guidance

This workflow is not for developers on free OpenAI accounts. Free tiers do not receive early model rollouts or Codex access to GPT-6 Astra. If you are on a free tier, upgrade to a paid ChatGPT plan before troubleshooting. Teams needing immediate, dedicated capacity should use direct API keys instead.

Our diagnosis would change if OpenAI reaches general availability for GPT-6 Astra across all user tiers. General availability alters the primary failure mode. Missing models would then indicate local client bugs or network blocks. Our advice would also shift if OpenAI eliminates the Enterprise admin toggle. For current token pricing and API economics, review our GPT-6 Astra API pricing guide.

To begin resolving your setup right now, run codex --version in your terminal to confirm you are on version 0.153.1 or higher.