Codex GPT-5-mini Error: Troubleshooting Guide

by Rajiv Sharma 46 views

Hey everyone, in this article, we're diving deep into a tricky issue encountered while trying to use the gpt-5-mini model with Codex. This comprehensive guide will walk you through the problem, the steps to reproduce it, the expected behavior, and what actually happened. Plus, we'll explore potential solutions and workarounds. So, if you're facing the dreaded "Unsupported model" error, you're in the right place! Let's get started and figure this out together.

Understanding the Issue: "Unsupported Model" Error with GPT-5-mini

When delving into the capabilities of OpenAI's Codex, one might encounter the frustrating "Unsupported model" error, particularly when attempting to utilize the gpt-5-mini model. This issue, categorized under openai and codex discussions, has been reported by users on various platforms, indicating a potential bug or configuration hiccup within the Codex environment. The error manifests as an unexpected status 400 Bad Request, accompanied by the message {"detail":"Unsupported model"}, leaving users unable to proceed with their desired tasks. This problem not only disrupts workflow but also raises questions about model availability and compatibility within the Codex ecosystem. It's crucial to understand the root causes of this error to effectively troubleshoot and find viable solutions, ensuring seamless interaction with Codex for future endeavors.

This error typically arises when launching Codex and explicitly specifying the gpt-5-mini model. Despite the model being selected in the configuration, Codex throws a 400 Bad Request error with the message {"detail":"Unsupported model"}. This indicates a mismatch between the requested model and what Codex can access or support. This can occur regardless of whether the model is specified with a date suffix (e.g., gpt-5-mini-2025-08-07) or without it (gpt-5-mini). The error persists even after verifying the user's account status, plan, and token usage, suggesting the issue is not related to account limitations or access rights. This unexpected behavior can significantly hinder the development and experimentation process, making it essential to identify the underlying cause and implement a suitable solution. Whether it's a configuration issue, a version incompatibility, or a potential bug, understanding the nuances of this error is paramount for efficient problem-solving.

Furthermore, the impact of this error extends beyond mere inconvenience. For developers and researchers relying on Codex for code generation, debugging, and creative problem-solving, the inability to utilize a specific model like gpt-5-mini can stall projects and limit the scope of experimentation. The error message itself provides little guidance, making it challenging for users to independently resolve the issue. This necessitates a deeper investigation into the Codex system, including potential version incompatibilities, configuration errors, or even temporary outages on the server-side. By dissecting the error message, the steps to reproduce the problem, and the environment in which it occurs, we can collectively work towards a resolution that restores the full functionality of Codex and ensures a seamless user experience. The frustration of encountering such errors underscores the importance of robust error handling and clear communication within software development, prompting both users and developers to seek clarity and solutions.

Reproducing the Bug: Step-by-Step Guide

To effectively tackle this issue, let's break down the steps to reproduce the bug. This will help you (and us!) verify the problem and test any potential solutions. By following these steps, you can reliably recreate the error and confirm whether a fix is working. Let's dive in:

  1. Launch Codex: Open your terminal and navigate to your workspace directory (e.g., ~/workspace/).
  2. Specify the Model: Use the command codex --model gpt-5-mini (or codex --model gpt-5-mini-2025-08-07) to launch Codex with the gpt-5-mini model.
  3. Initiate Interaction: Once Codex is running, type hello and press Enter to initiate a simple interaction.
  4. Observe the Error: You should see the error message `🖐 unexpected status 400 Bad Request: {