vitejs/vite · error · Error

No corresponding modern polyfill chunk found for ${htmlFilen

Error message

No corresponding modern polyfill chunk found for ${htmlFilename}

What it means

Thrown in transformIndexHtml when modern polyfills were detected (modernPolyfills.size > 0) but no modern polyfill chunk was associated with the current HTML entry's facadeModuleId. The plugin expects that if polyfills are collected, the buildPolyfillChunk call in generateBundle created a chunk and registered it in facadeToModernPolyfillMap. A missing entry means the polyfill chunk wasn't built or the facadeModuleId didn't match any chunk in the bundle during registration.

Source

Thrown at packages/plugin-legacy/src/index.ts:765

        const modernPolyfillFilename = facadeToModernPolyfillMap.get(
          chunk.facadeModuleId,
        )

        if (modernPolyfillFilename) {
          tags.push({
            tag: 'script',
            attrs: {
              type: 'module',
              crossorigin: true,
              src: toAssetPathFromHtml(
                modernPolyfillFilename,
                chunk.facadeModuleId!,
                config,
              ),
            },
          })
        } else if (modernPolyfills.size) {
          throw new Error(
            `No corresponding modern polyfill chunk found for ${htmlFilename}`,
          )
        }
      }

      if (!genLegacy) {
        return { html, tags }
      }

      // 2. inject importmaps
      if (config.build.chunkImportMap) {
        const importMap = facadeToLegacyImportMap.get(chunk.facadeModuleId)!
        const decoder = new TextDecoder()
        tags.push({
          tag: 'script',
          attrs: { type: 'systemjs-importmap' },
          children:
            typeof importMap.source === 'string'

View on GitHub (pinned to 89620f09af)

Solutions

If you explicitly set modernPolyfills to true, try switching to an explicit array (e.g., modernPolyfills: ['es.array.flat']) to control which polyfills are included.
Check that your rollupOptions.input HTML entries resolve to stable, real file paths (not virtual IDs).
Update plugin-legacy; facadeModuleId matching has had fixes in newer versions.
If using a custom plugin that alters entry resolution, ensure it preserves the original facadeModuleId.

Example fix

// before
legacy({ modernPolyfills: true })
// after — explicit list avoids auto-detection facade mismatches
legacy({ modernPolyfills: [
  'es.array.flat', 'es.promise', 'es.object.from-entries'
] })

Defensive patterns

Strategy: validation

Validate before calling

// Pre-validate that HTML entries have stable facadeModuleId values
function validateHtmlEntries(input) {
  const entries = typeof input === 'object' ? Object.values(input) : [input]
  for (const entry of entries) {
    if (typeof entry !== 'string' || !entry.endsWith('.html')) {
      console.warn(`Input ${entry} may not resolve to a stable HTML facadeModuleId`)
    }
  }
}
validateHtmlEntries(config.build.rollupOptions.input)

Type guard

function hasExplicitModernPolyfills(options: Options): boolean {
  return Array.isArray(options.modernPolyfills)
}

// prefer explicit to avoid auto-detection facade issues
if (!hasExplicitModernPolyfills(opts)) {
  console.warn('Consider setting modernPolyfills to an explicit array for multi-page apps')
}

Try / catch

try {
  await build({ plugins: [legacy({ modernPolyfills: explicitList })] })
} catch (e) {
  if (e.message.includes('No corresponding modern polyfill chunk')) {
    console.error('Polyfill/entry facade mismatch. Try explicit modernPolyfills array.')
  }
  throw e
}

Prevention

For multi-page apps, use explicit modernPolyfills arrays instead of auto-detection (true).
Ensure rollupOptions.input HTML files resolve to real file system paths.
Test each HTML entry independently to isolate which one triggers the mismatch.

When it happens

Trigger: Multi-page apps where HTML entry files have unusual facadeModuleId values (e.g., virtual modules, custom resolveId). Also triggered when modernPolyfills is set to true (auto-detect) and polyfills are found, but the entry chunk's facadeModuleId is null or doesn't match what was registered during buildPolyfillChunk's bundle iteration.

Common situations: Using custom HTML entry resolution, multi-page setups with rollupOptions.input containing HTML files, or plugins that intercept entry module IDs. Can also happen when MPA input keys don't align with facadeModuleId after transformation.

Related errors

AI-assisted analysis of vitejs/vite@89620f09af (2026-08-03). Data as JSON: /data/errors/15e85c39acce792f.json. Report an issue: GitHub.