bug: GPT-5 model is not working 'low' is not supported with the 'gpt-5-chat-latest' model

The issue

Trying to use gpt-5 results in the error:

AI_APICallError: Unsupported value: 'low' is not supported with the 'gpt-5-chat-latest' model. Supported values are: 'medium'.

Repro

Using /models select GPT-5 Chat (latest)
Try and use it

Workaround

A simple workaround is possible

  "provider": {
    "openai": {
      "models": {
        "gpt-5-fixed": {
          "options": {
            "reasoningEffort": "high",
            "textVerbosity": "medium", // <--- changed this from low to medium
            "reasoningSummary": "auto",
            "include": ["reasoning.encrypted_content"]
          }
        }
      }
    }
  }

Version

opencode 0.5.4

This issue might be a duplicate of existing issues. Please check:

GPT-5 Unsupported parameter reasoning.effort #1859: GPT-5 Unsupported parameter reasoning.effort (similar model parameter compatibility issues)
GPT-5 Not working on Azure - Functions not supported #1918: GPT-5 Not working on Azure - Functions not supported (GPT-5 compatibility issues)
Reasoning effort from opencode.json not passed through for Azure models #1823: Reasoning effort from opencode.json not passed through for Azure models (parameter configuration issues)
BUG: gpt-5 azure Unsupported parameter: 'max_tokens' #1697: BUG: gpt-5 azure Unsupported parameter: 'max_tokens' (GPT-5 parameter support issues)

Feel free to ignore if none of these address your specific case.

@Ramblurr

@Ramblurr I cannot replicate but I would recommend using gpt-5 instead of gpt-5-chat-latest I think openai is experimenting quite a bit on their end and I don't know if we can really solve for all breaking changes they may make on the fly

From openai docs:

GPT-5 Chat points to the GPT-5 snapshot currently used in ChatGPT. We recommend GPT-5 for most API usage, but feel free to use this GPT-5 Chat model to test our latest improvements for chat use cases.

closing since this doesn't seem to be an issue anymore

Navigation Menu

Repository navigation

bug: GPT-5 model is not working `'low' is not supported with the 'gpt-5-chat-latest' model` #1984

The issue

Repro

Workaround

Version

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

bug: GPT-5 model is not working 'low' is not supported with the 'gpt-5-chat-latest' model #1984

Description

The issue

Repro

Workaround

Version

Activity

github-actions commented on Aug 16, 2025

rekram1-node commented on Aug 16, 2025

rekram1-node commented on Aug 18, 2025

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

bug: GPT-5 model is not working `'low' is not supported with the 'gpt-5-chat-latest' model` #1984