babel/babel · error · Error

`isPluginRequired` has been removed in Babel 8. Please use `

Error message

`isPluginRequired` has been removed in Babel 8. Please use `isRequired` from `@babel/helper-compilation-targets` instead.

What it means

@babel/preset-env still exports `isPluginRequired` for backwards compatibility, but its body (index.ts:40-44) unconditionally throws. In Babel 8 the capability moved to `@babel/helper-compilation-targets` as `isRequired`, so any call to the old export is dead code.

Source

Thrown at packages/babel-preset-env/src/index.ts:41

import pluginCoreJS3 from "babel-plugin-polyfill-corejs3";

import getTargets, {
  prettifyTargets,
  filterItems,
} from "@babel/helper-compilation-targets";
import type { Targets } from "@babel/helper-compilation-targets";
import availablePlugins from "./available-plugins.ts";
import { declarePreset } from "@babel/helper-plugin-utils";

import type { BuiltInsOption, ModuleOption, Options } from "./types.d.ts";
export type { Options };

/**
 * @deprecated Use `isRequired` from `@babel/helper-compilation-targets` instead.
 */
// eslint-disable-next-line @typescript-eslint/no-unused-vars
export function isPluginRequired(targets: Targets, support: Targets) {
  throw new Error(
    "`isPluginRequired` has been removed in Babel 8. Please use `isRequired` from `@babel/helper-compilation-targets` instead.",
  );
}

function filterStageFromList(
  list: Record<string, Targets>,
  stageList: Set<string>,
) {
  return Object.keys(list).reduce((result, item) => {
    if (!stageList.has(item)) {
      // @ts-expect-error todo: refine result types
      result[item] = list[item];
    }

    return result;
  }, {});
}

View on GitHub (pinned to 06b6eae39d)

Solutions

Replace the import: `import { isRequired } from '@babel/helper-compilation-targets'`.
Call `isRequired(targets, pluginCompatData)` with the same two-argument shape.

Example fix

// before
import { isPluginRequired } from "@babel/preset-env";
isPluginRequired(targets, { chrome: "60" });
// after
import { isRequired } from "@babel/helper-compilation-targets";
isRequired({ chrome: "60" }, pluginCompat);

Defensive patterns

Strategy: validation

Validate before calling

// do not import isPluginRequired from @babel/preset-env
import { isRequired } from "@babel/helper-compilation-targets";

Prevention

Grep the codebase for `isPluginRequired` immediately after upgrading.
Switch to `isRequired` from `@babel/helper-compilation-targets` proactively.

When it happens

Trigger: Importing `{ isPluginRequired }` from `@babel/preset-env` and invoking it: `isPluginRequired(targets, support)`.

Common situations: Build scripts, CLIs, or codemods that computed whether a transform was needed via preset-env's old export and were never migrated during the Babel 8 upgrade.

Related errors

AI-assisted analysis of babel/babel@06b6eae39d (2026-08-03). Data as JSON: /data/errors/cb0c4075a458305c.json. Report an issue: GitHub.