oxc-project/oxc · error · OxcDiagnostic

Effect callbacks are synchronous to prevent race conditions.

Error message

Effect callbacks are synchronous to prevent race conditions.

What it means

Raised by react/exhaustive-deps when an effect callback is declared async (returns a Promise). React expects effects to be synchronous; async effects cause race conditions because cleanup cannot cancel pending promises.

Source

Thrown at crates/oxc_linter/src/rules/react/exhaustive_deps.rs:70

    OxcDiagnostic::warn(format!(
        "React Hook {hook_name} does nothing when called with only one argument."
    ))
    .with_label(span)
    .with_help("Did you forget to pass an array of dependencies?")
    .with_error_code_scope(SCOPE)
}

fn unknown_dependencies_diagnostic(hook_name: &str, span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn(format!(
        "React Hook {hook_name} received a function whose dependencies are unknown."
    ))
    .with_help("Pass an inline function instead.")
    .with_label(span)
    .with_error_code_scope(SCOPE)
}

fn async_effect_diagnostic(span: Span) -> OxcDiagnostic {
    OxcDiagnostic::warn("Effect callbacks are synchronous to prevent race conditions.")
        .with_label(span)
        .with_help("Consider putting the asynchronous code inside a function and calling it from the effect.")
        .with_error_code_scope(SCOPE)
}

fn missing_dependency_diagnostic(
    hook_name: &str,
    deps: &[Name<'_>],
    span: Span,
    mutable_ref_dependency: Option<&str>,
) -> OxcDiagnostic {
    let single = deps.len() == 1;
    let deps_pretty = if single {
        format!("'{}'", deps[0])
    } else {
        let mut iter = deps.iter();
        let all_but_last = iter
            .by_ref()

View on GitHub (pinned to e1e7af627c)

Solutions

1. Move the async work into an inner function and await it inside the synchronous effect body.
2. Handle cleanup/cancellation explicitly (e.g. via an ignore flag or AbortController).

When it happens

Trigger: Thrown at crates/oxc_linter/src/rules/react/exhaustive_deps.rs:70 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of oxc-project/oxc@e1e7af627c (2026-08-20). Data as JSON: /api/errors/7f367d3103875665. Report an issue: GitHub.