"The requested model 'gpt-5.3-codex' does not exist."

[aschoettler]

What version of Code is running?

code 0.6.59

Which model were you using?

gpt-5.3-codex

What platform is your computer?

Linux 6.12.67 aarch64 unknown

What terminal emulator and version are you using (if applicable)?

Ghostty

What steps can reproduce the bug?

I re-authenticated to codex and coder via Chat GPT, but I'm getting an error when using gpt-5.3-codex:

ERROR: [transport] failed to start stream: unexpected status 400 Bad Request: {
  "error": {
    "message": "The requested model 'gpt-5.3-codex' does not exist.",
    "type": "invalid_request_error",
    "param": "model",
    "code": "model_not_found"
  }
}

To troubleshoot the issue I tried setting CODEX_HOME to ~/.codex instead of ~/.code and still had the same issues.

To reproduce:

which coder
coder --version
CODEX_HOME=~/.codex coder login status
CODEX_HOME=~/.codex coder exec --skip-git-repo-check -c model="gpt-5.2-codex" "ping"
CODEX_HOME=~/.codex codex exec --skip-git-repo-check -c model="gpt-5.3-codex" "ping"
CODEX_HOME=~/.codex coder exec --skip-git-repo-check -c model="gpt-5.3-codex" "ping"

Output:

/run/current-system/sw/bin/coder
code 0.6.59
Logged in using ChatGPT

The next outputs show that gpt-5.3-codex is authenticaed for codex, but won't work for code:

[2026-02-06T22:25:44] OpenAI Codex v0.0.0 (research preview)
[2026-02-06T22:25:44] binary: /nix/store/n7c7f1dh4483ax8pwd3y3c4b8kd0ws0v-coder-0.6.59/bin/coder
--------
workdir: /home/user
model: gpt-5.2-codex
provider: openai
approval: never
sandbox: workspace-write [workdir, /tmp, $TMPDIR] (network access enabled)
reasoning effort: medium
reasoning summaries: auto
--------
[2026-02-06T22:25:44] User instructions:
ping

[2026-02-06T22:25:45] thinking

**Noting need to respond to ping**
[2026-02-06T22:25:45] codex

pong
[2026-02-06T22:25:45] tokens used: 6,487```

OpenAI Codex v0.98.0 (research preview)
--------
workdir: /home/user
model: gpt-5.3-codex
provider: openai
approval: never
sandbox: workspace-write [workdir, /tmp, $TMPDIR] (network access enabled)
reasoning effort: medium
reasoning summaries: auto
session id: 019c3510-acc2-7842-abae-ee7603a6f80f
--------
user
ping
mcp startup: no servers

thinking
**Responding with pong**
codex
pong
tokens used
90
pong

[2026-02-06T22:27:16] OpenAI Codex v0.0.0 (research preview)
[2026-02-06T22:27:16] binary: /nix/store/n7c7f1dh4483ax8pwd3y3c4b8kd0ws0v-coder-0.6.59/bin/coder
--------
workdir: /home/user
model: gpt-5.3-codex
provider: openai
approval: never
sandbox: workspace-write [workdir, /tmp, $TMPDIR] (network access enabled)
reasoning effort: medium
reasoning summaries: auto
--------
[2026-02-06T22:27:16] User instructions:
ping
[2026-02-06T22:27:17] ERROR: [transport] failed to start stream: unexpected status 400 Bad Request: {
  "error": {
    "message": "The requested model 'gpt-5.3-codex' does not exist.",
    "type": "invalid_request_error",
    "param": "model",
    "code": "model_not_found"
  }
}

What is the expected behavior?

• "pong" response

What do you see instead?

The requested model 'gpt-5.3-codex' does not exist.

Additional information

• I'm currently using a Chat GPT business account
• I don't have an API key and API fallback is OFF in the code settings.
• GPT's hypothesis: code is still routing through the OpenAI API provider even with ChatGPT login, and gpt-5.3-codex is not exposed on the API yet.
• The environment has no OPENAI_API_KEY set, no OPENAI_BASE_URL, and no configured model-provider overrides.

Thanks for your help and awesome work! Let me know if I can do any other steps to help debug.

[aschoettler]

Update: Fixed on my branch here. The error is because the API requests from code have headers containing a version number that is too low. My branch fixes this by submitting requests using a minimum version number, comparing code's version number to the version string grabbed from announcement_tip.toml which will hopefully continue to match upstream.

Tested on macos and linux (nixos).

[zemaj]

Hmm that's odd. It's working fine for me on multiple accounts. Will investigate further.

[aschoettler]

I did some more testing but I went way past the compaction threshold in codex so despite using 5.3 to debug, there was a lot of back and forth testing different hypotheses and revising different assumptions, and not a clear resolution in my opinion.

Bottom line, I think the nix build environment doesn't have CODEX_VERSION, and in that case defaults to CARGO_PKG_VERSION which is 0.0.0. Github release builds however set CODEX_VERSION and provide it to the build-time environment.

After I made that branch I linked, I had the idea that the build environment was the problem. In testing, it sure looked like setting CARGO_VERSION=0.6.x (at build time) caused requests to fail and CARGO_VERSION=0.98.0 got requests to succeed. And I think thats why my linked branch works, because it uses a higher value in the headers.

But that doesn't explain why other people don't have the same issue, because if other code users are sending requests with version 0.6.xx, and gpt 5.3 works in that case, then there must be something else causing my requests to fail when building from main. Nevertheless my branch resolves the problem for me, so I have no idea what the real cause is.

[tannn]

I have the same issue on my mac (fresh install)

[aaronedev]

+1 same issues for me i thought because no one was talking about it that i was doing something weird

[aaronedev]

Update: Fixed on my branch here. The error is because the API requests from code have headers containing a version number that is too low. My branch fixes this by submitting requests using a minimum version number, comparing code's version number to the version string grabbed from announcement_tip.toml which will hopefully continue to match upstream.

Tested on macos and linux (nixos).

thank you going to use ur fork for now💖