Codex & Claude error message explainers

What a specific Codex or Claude error message actually means, and whether it's related to your usage limit reset or something else entirely (server capacity, a bug, an account issue) — the index of every error explainer on this site.

• "Selected model is at capacity" in Codex: Not a Usage Limit

  "Selected model is at capacity. Please try a different model." is Codex's own server-overload error (HTTP 503), separate in the code from a usage-limit reset. Here's how to tell the two apart, what OpenAI's Codex team has said about it, and what to check next.

  Updated 2026-09-23

Looking for when the reset itself happens, not what an error message means? See Codex reset history or Claude reset history.