This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite.
Open 💬 4 comments Opened Jul 2, 2026 by 13274531996wang-wq
💡 Likely answer: A maintainer (github-actions[bot], contributor)
responded on this thread — see the highlighted reply below.
What version of the Codex App are you using (From “About Codex” dialog)?
App 端版本：26.623.11225.0 ; CLI 端版本：codex-cli 0.142.5
What subscription do you have?
plus
What platform is your computer?
Microsoft Windows 11 家庭版 中文版，64-bit，内核版本 10.0.26200，构建号 26200。
What issue are you seeing?
2026年6月27日codex客户端提示我更新，在更新之后我所有的对话、项目使用5.5模型均不能使用，截止到7月2日，codex多次更新之后还是不能使用5.5模型，我所有之前使用5.5模型开展的项目和对话全都不能继续进行，只能通过CLI端改成5.4模型进行操作，所有使用5.5模型的报错均为“This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite.”。
What steps can reproduce the bug?
我完全不知道为什么会发生这样的事情，仅仅是在我更新了一次客户端之后，我的电脑就完全不能使用5.5模型了。019f1cab-f14b-7473-ac24-3a4721507205
What is the expected behavior?
我希望能尽快的解决这个问题，无论是因为什么，这种情况已经非常影响我的正常使用了
Additional information
_No response_
4 Comments
English translation:
What version of the Codex App are you using (From “About Codex” dialog)?
App version: 26.623.11225.0; CLI version: codex-cli 0.142.5
What subscription do you have?
plus
What platform is your computer?
Microsoft Windows 11 Home Chinese edition, 64-bit, kernel version 10.0.26200, build 26200.
What issue are you seeing?
On June 27, 2026, the Codex client prompted me to update. After updating, all of my conversations and projects using the 5.5 model became unusable. As of July 2, even after multiple Codex updates, I still cannot use the 5.5 model. All of the projects and conversations where I previously used the 5.5 model can no longer continue. I can only switch to the 5.4 model through the CLI to operate. All errors when using the 5.5 model are: “This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite.”
What steps can reproduce the bug?
I have absolutely no idea why this happened. After I updated the client once, my computer completely lost the ability to use the 5.5 model. 019f1cab-f14b-7473-ac24-3a4721507205
What is the expected behavior?
I hope this issue can be resolved as soon as possible. Whatever the cause is, this situation has already seriously affected my normal use.
Additional information
_No response_
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我在 Codex Desktop 上使用 ChatGPT auth 时，gpt-5.5 无法使用，但 gpt-5.4 可以正常使用。
环境：App 26.623.11225.0，CLI 0.142.5，Windows 11 64-bit build 26200。
当前 provider 是 chatgpt-http，没有 API key。
执行 codex.exe exec -m gpt-5.5 ... 时固定报错：
This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite.
同机同配置下，gpt-5.4 返回 OK。我已经更换过 ChatGPT 账号、也更换过 SSR 出口 IP，结果不变。看起来像是 ChatGPT auth / chatgpt-http / Responses-Lite 链路对 gpt-5.5 的兼容或路由问题。失败线程 ID：019f2208-9549-7441-9f02-e879904eba83，019f221a-c74b-71b1-8269-04003295444c。
不知道你有没有使用不同账号，不同账号即使是同一个gpt-5.5，同是plus plan，有的账号支持responses-lite（就是一个‘exec' tool执行各种sub tools）,有的账号不支持。
如果你用proxy的话，其实只要加个header rule把这个header移除就可以：
x-openai-internal-codex-responses-lite: true
不然自己写个简单的proxy也可以。