openai/codex · error · CodexErr

Codex ran out of room in the model's context window. Start a

Error message

Codex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying.

What it means

Error "Codex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying." thrown in openai/codex.

Source

Thrown at codex-rs/protocol/src/error.rs:94

#[derive(Error, Debug, EnumDiscriminants)]
#[strum_discriminants(name(CodexErrKind))]
#[strum_discriminants(derive(serde::Serialize))]
#[strum_discriminants(serde(rename_all = "snake_case"))]
#[strum_discriminants(doc = "The payload-free semantic category used for analytics.")]
pub enum CodexErrorDetails {
    #[error("turn aborted. Something went wrong? Hit `/feedback` to report the issue.")]
    TurnAborted,

    #[error("shared rollout token budget exhausted")]
    SessionBudgetExceeded,

    /// Returned by ResponsesClient when the SSE stream disconnects or errors out **after** the HTTP
    /// handshake has succeeded but **before** it finished emitting `response.completed`.
    ///
    /// The Session loop treats this as a transient error and will automatically retry the turn.
    #[error("stream disconnected before completion: {0}")]
    Stream(String),
    #[error(
        "Codex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying."
    )]
    ContextWindowExceeded,
    #[error("no thread with id: {0}")]
    ThreadNotFound(ThreadId),
    #[error("agent thread limit reached")]
    AgentLimitReached { max_threads: usize },
    #[error("session configured event was not the first event in the stream")]
    SessionConfiguredNotFirstEvent,
    /// Returned by run_command_stream when the spawned child process timed out (10s).
    #[error("timeout waiting for child process to exit")]
    Timeout,
    #[error("request timed out")]
    RequestTimeout,
    /// Returned by run_command_stream when the child could not be spawned (its stdout/stderr pipes
    /// could not be captured). Analogous to the previous `CodexError::Spawn` variant.
    #[error("spawn failed: child stdout/stderr not captured")]
    Spawn,

View on GitHub (pinned to 339751715c)

When it happens

Trigger: Thrown at codex-rs/protocol/src/error.rs:94 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/bf9d7cb3a25351e0. Report an issue: GitHub.