oxc-project/oxc · error · OxcDiagnostic

Unsafe lifecycle method `{method_name}` is not allowed

Error message

Unsafe lifecycle method `{method_name}` is not allowed

What it means

Raised by react/no_unsafe when a class declares a legacy unsafe lifecycle method (`componentWillMount`, `componentWillReceiveProps`, `componentWillUpdate`, or their UNSAFE_-prefixed forms). At the throw site the method is scheduled for removal/already unsupported under async rendering (React 16.3+/17+ with StrictMode double-invocation), and the message indicates the supported replacement (componentDidMount, getDerivedStateFromProps, componentDidUpdate). no_unsafe_diagnostic fires from run() for each matching class method, gated by the configured React version.

Source

Thrown at crates/oxc_linter/src/rules/react/no_unsafe.rs:26

use crate::{
    AstNode,
    config::ReactVersion,
    context::{ContextHost, LintContext},
    rule::{DefaultRuleConfig, Rule},
    utils::{get_parent_component, is_es5_component},
};

fn no_unsafe_diagnostic(method_name: &str, span: Span) -> OxcDiagnostic {
    let replacement = match method_name {
        "componentWillMount" | "UNSAFE_componentWillMount" => "componentDidMount",
        "componentWillReceiveProps" | "UNSAFE_componentWillReceiveProps" => {
            "getDerivedStateFromProps"
        }
        "componentWillUpdate" | "UNSAFE_componentWillUpdate" => "componentDidUpdate",
        _ => "alternative lifecycle methods",
    };

    OxcDiagnostic::warn(format!("Unsafe lifecycle method `{method_name}` is not allowed"))
        .with_help(format!(
            "Use `{replacement}` instead. See https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html"
        ))
        .with_label(span)
}

#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema, Default)]
#[serde(rename_all = "camelCase", default, deny_unknown_fields)]
struct NoUnsafeConfig {
    /// Whether to check for the non-prefixed lifecycle methods.
    /// If `true`, this means `componentWillMount`, `componentWillReceiveProps`,
    /// and `componentWillUpdate` will also be flagged, rather than just the
    /// UNSAFE_ versions. It is recommended to set this to `true` to fully
    /// avoid unsafe lifecycle methods.
    check_aliases: bool,
}

#[derive(Debug, Default, Clone, Deserialize, Serialize, JsonSchema)]

View on GitHub (pinned to e1e7af627c)

Solutions

1. Migrate componentWillMount to componentDidMount.
2. Migrate componentWillReceiveProps to getDerivedStateFromProps.
3. Migrate componentWillUpdate to componentDidUpdate or getSnapshotBeforeUpdate.

When it happens

Trigger: Thrown at crates/oxc_linter/src/rules/react/no_unsafe.rs:26 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/4091d74abf38cb69. Report an issue: GitHub.