webpack/webpack · error · Error

library type "module" is only allowed when 'experiments.outp

Error message

library type "module" is only allowed when 'experiments.outputModule' is enabled

What it means

Error "library type "module" is only allowed when 'experiments.outputModule' is enabled" thrown in webpack/webpack.

Source

Thrown at lib/WebpackOptionsApply.js:503

				}
			}
		}

		new JavascriptModulesPlugin().apply(compiler);

		new JsonModulesPlugin().apply(compiler);
		new AssetModulesPlugin({
			sideEffectFree: options.experiments.futureDefaults
		}).apply(compiler);

		if (!options.experiments.outputModule) {
			if (options.output.module) {
				throw new Error(
					"'output.module: true' is only allowed when 'experiments.outputModule' is enabled"
				);
			}
			if (options.output.enabledLibraryTypes.includes("module")) {
				throw new Error(
					"library type \"module\" is only allowed when 'experiments.outputModule' is enabled"
				);
			}
			if (options.output.enabledLibraryTypes.includes("modern-module")) {
				throw new Error(
					"library type \"modern-module\" is only allowed when 'experiments.outputModule' is enabled"
				);
			}
			if (
				options.externalsType === "module" ||
				options.externalsType === "module-import"
			) {
				throw new Error(
					"'externalsType: \"module\"' is only allowed when 'experiments.outputModule' is enabled"
				);
			}
		}

View on GitHub (pinned to 318421ea8a)

Solutions

1. Enable experiments.outputModule: true in the webpack configuration when using output.library.type: 'module'.

When it happens

Trigger: Thrown at lib/WebpackOptionsApply.js:503 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of webpack/webpack@318421ea8a (2026-08-03). Data as JSON: /data/errors/c1ac3479354b52db.json. Report an issue: GitHub.