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"The requested model is not supported." and "model gpt-5.1-codex is not accessible via the /chat/completions endpoint" for github copilot provider #4819

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"The requested model is not supported." and "model gpt-5.1-codex is not accessible via the /chat/completions endpoint" for github copilot provider#4819
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bugSomething isn't workingopentuiThis relates to changes in v1.0, now that opencode uses opentui

Description

@PadishahIII
PadishahIII
opened on Nov 27, 2025

Description

When I try to build using Github copilot's claude-sonnet-4.5 model, the error occur: "The requested model is not supported."

Image

But I've enabled this model following the endpoint in the error message:

Image

It's strange since I've used this model in opencode one or two weeks ago and it used to work fine.

And second, opencode says the 'gpt-5.1-codex' model is not accessible in github copilot, but it's present indeed:

Image

OpenCode version

1.0.119

Steps to reproduce

  1. run opencode and switch to github copilot's claude-sonnet-4.5
  2. send whatever prompt

Screenshot and/or share link

https://opencode.ai/s/hXWfg5i2

Operating System

macOS 15.6

Terminal

alacritty

Activity

  1. PadishahIII
    added
    bugSomething isn't working
    on Nov 27, 2025
  2. github-actions
    added
    opentuiThis relates to changes in v1.0, now that opencode uses opentui
    on Nov 27, 2025

  3. github-actions commented on Nov 27, 2025

    @github-actions
    github-actionsBot
    on Nov 27, 2025 – with GitHub Actions
    Contributor

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

    These issues relate to:

    1. Claude Sonnet 4.5 model errors with GitHub Copilot (similar to your first issue)
    2. GPT-5-Codex and GPT-5.1-Codex requiring the /responses API endpoint instead of /chat/completions (similar to your second issue)

    The underlying cause appears to be that GitHub Copilot's newer models (gpt-5-codex, gpt-5.1-codex) use the /responses API endpoint, but OpenCode is still trying to use the /chat/completions endpoint for them.

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

  4. PadishahIII commented on Nov 27, 2025

    @PadishahIII
    PadishahIII
    on Nov 27, 2025
    Author

    ok, i've fixed that according to #4626

  5. PadishahIII
    closed this as completedon Nov 27, 2025

  6. jomach commented on Feb 23, 2026

    @jomach
    jomach
    on Feb 23, 2026

    Still same error now.

    Image Also tried mini
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