webpack/webpack · error · Error

JavascriptModulesPlugin error: JavascriptModulesPlugin.getCo

Error message

JavascriptModulesPlugin error: JavascriptModulesPlugin.getCompilationHooks().renderContent plugins should return something

What it means

Thrown during renderChunk (the non-entry chunk render path in JavascriptModulesPlugin) when the renderContent SyncWaterfallHook returns a falsy value after being called. The hook chains plugin outputs; if the last plugin to tap returns null/undefined (and no plugin returned a valid Source), the post-hook check throws.

Source

Thrown at lib/javascript/JavascriptModulesPlugin.js:1070

				chunkRenderContext,
				registryModules,
				(module, renderInObject) =>
					this.renderModule(
						module,
						{ ...chunkRenderContext, factory: true, renderInObject },
						hooks
					)
			) || new RawSource("{}");
		let source = tryRunOrWebpackError(
			() => hooks.renderChunk.call(moduleSources, chunkRenderContext),
			"JavascriptModulesPlugin.getCompilationHooks().renderChunk"
		);
		source = tryRunOrWebpackError(
			() => hooks.renderContent.call(source, chunkRenderContext),
			"JavascriptModulesPlugin.getCompilationHooks().renderContent"
		);
		if (!source) {
			throw new Error(
				"JavascriptModulesPlugin error: JavascriptModulesPlugin.getCompilationHooks().renderContent plugins should return something"
			);
		}
		source = InitFragment.addToSource(
			source,
			chunkRenderContext.chunkInitFragments,
			chunkRenderContext
		);
		source = tryRunOrWebpackError(
			() => hooks.render.call(source, chunkRenderContext),
			"JavascriptModulesPlugin.getCompilationHooks().render"
		);
		if (!source) {
			throw new Error(
				"JavascriptModulesPlugin error: JavascriptModulesPlugin.getCompilationHooks().render plugins should return something"
			);
		}
		chunk.rendered = true;

View on GitHub (pinned to 318421ea8a)

Solutions

Ensure your renderContent tap always returns a Source (or the input source unchanged) — never null or undefined.
Return the incoming `source` argument as a pass-through when your plugin has no transformation to apply.
Audit all plugins tapping renderContent to find which one returns falsy for the failing chunk.
If a third-party plugin is responsible, check for an updated version compatible with your webpack major.

Example fix

// before
hooks.renderContent.tap('MyPlugin', (source, ctx) => {
  return transformOrNull(source); // may return null
});
// after
hooks.renderContent.tap('MyPlugin', (source, ctx) => {
  return transformOrNull(source) || source;
});

Defensive patterns

Strategy: validation

Validate before calling

// When tapping renderContent, always guarantee a return
hooks.renderContent.tap('MyPlugin', (source, ctx) => {
  const result = myTransform(source);
  return result !== null && result !== undefined ? result : source;
});

Prevention

Always return a Source from renderContent taps.
Use `return source;` as the default fallback in taps.
Test plugins against both entry and non-entry chunks.

When it happens

Trigger: A plugin tapping JavascriptModulesPlugin.getCompilationHooks().renderContent for a non-entry chunk returns null, undefined, or an empty string instead of a Source object, and no other plugin in the chain provides a valid Source.

Common situations: Custom render plugins (minification wrappers, source transform plugins) that conditionally return nothing; a plugin authored for entry chunks only that inadvertently taps renderContent for all chunks; version incompatibility where a plugin's render logic changed.

Related errors

AI-assisted analysis of webpack/webpack@318421ea8a (2026-08-03). Data as JSON: /data/errors/eb1f4cce6c38b4d5.json. Report an issue: GitHub.