Build fails with ENOTDIR error for `_unenv/workerd/process.mjs` when using `cloudflare-pages` preset

[felixgabler]

Environment

• Operating System: Darwin
• Node Version: v22.11.0
• Nuxt Version: 3.16.2
• CLI Version: 3.24.0
• Nitro Version: 2.11.8
• Package Manager: bun@1.2.7
• Builder: -
• User Config: compatibilityDate, modules, devtools, imports, components, css, runtimeConfig, routeRules, app, supabase, i18n, cookieControl, $production, stripe, sitemap, pwa, router, sourcemap, sentry, build, eslint, nitro, vite
• Runtime Modules: ./modules/supabase-nuxt/src/module.ts, @unlok-co/nuxt-stripe@4.0.2, nuxt-i18n-micro@1.83.0, @nuxtjs/fontaine@0.5.0, @vueuse/nuxt@13.0.0, @nuxtjs/sitemap@7.2.9, @dargmuesli/nuxt-cookie-control@8.6.1, floating-vue/nuxt@5.2.2, @nuxt/eslint@1.3.0, @vite-pwa/nuxt@1.0.0, @nuxt/scripts@0.11.5, @sentry/nuxt/module@9.10.1, @nuxthub/core@0.8.23
• Build Modules: -

Reproduction

Will try to set up a repository with a reproduction asap but wanted to already get this out here

Describe the bug

When attempting to build a Nuxt 3.16.2 project using the cloudflare-pages preset (required for Nuxt Hub deployment), the build fails during the Nitro server build step.

The specific error is:

[nitro 4:52:56 PM] ERROR Error: Could not load /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/: ENOTDIR: not a directory, open '/my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/'

This suggests that the build process is incorrectly appending a trailing slash and trying to read the file node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs as if it were a directory.

Additional context

• This error occurs specifically when using the cloudflare-pages preset.
• We are considering a migration from Vercel to Nuxt Hub, and this error is blocking our deployment and evaluation process.
• We previously encountered an issue with papaparse similar to nitrojs/nitro#3071 which was resolved by adding a replace rule to the nitro config, but this ENOTDIR error seems unrelated.
• The problematic file appears to be related to Node.js process polyfills for the Cloudflare Workers environment: nitrojs/nitro/.../process.mjs

Logs

[nitro 5:15:31 PM] ℹ Building Nuxt Nitro server (preset: cloudflare-pages, compatibility date: 2024-07-05)
node_modules/mime/dist/src/Mime.js (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/mime/dist/src/Mime.js (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/metrics/NoopMeter.js (16:17): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/metrics/NoopMeter.js (16:25): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/core.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/core.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/core.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/core.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/core.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/core.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/core.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/core.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/context.js (16:14): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/context.js (16:22): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/context.js (32:21): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/context.js (32:29): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/diag.js (16:14): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/diag.js (16:22): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/diag.js (32:21): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/api/diag.js (32:29): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/baggage/internal/baggage-impl.js (16:14): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/baggage/internal/baggage-impl.js (16:22): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/baggage/internal/baggage-impl.js (32:16): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/baggage/internal/baggage-impl.js (32:24): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/responses/ResponseStream.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/responses/ResponseStream.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/responses/ResponseStream.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/responses/ResponseStream.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/diag/ComponentLogger.js (16:14): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/diag/ComponentLogger.js (16:22): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/diag/ComponentLogger.js (32:21): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/diag/ComponentLogger.js (32:29): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/context/NoopContextManager.js (16:14): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/context/NoopContextManager.js (16:22): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/context/NoopContextManager.js (32:21): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@opentelemetry/api/build/esm/context/NoopContextManager.js (32:29): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/MessageStream.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/MessageStream.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/MessageStream.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/MessageStream.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/internal/decoders/line.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/internal/decoders/line.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/internal/decoders/line.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/internal/decoders/line.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/EventStream.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/EventStream.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/EventStream.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/EventStream.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/internal/decoders/line.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/internal/decoders/line.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/internal/decoders/line.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/internal/decoders/line.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/AssistantStream.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/AssistantStream.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/AssistantStream.mjs (6:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/AssistantStream.mjs (6:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/BetaMessageStream.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/BetaMessageStream.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/BetaMessageStream.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/@anthropic-ai/sdk/lib/BetaMessageStream.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/ChatCompletionStream.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/ChatCompletionStream.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/ChatCompletionStream.mjs (7:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/ChatCompletionStream.mjs (7:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/AbstractChatCompletionRunner.mjs (1:30): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
node_modules/openai/lib/AbstractChatCompletionRunner.mjs (1:38): The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten

[nitro 5:16:21 PM]  ERROR  Error: Could not load /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/: ENOTDIR: not a directory, open '/my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/'


undefined


[5:16:21 PM]  ERROR  Could not load /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/: ENOTDIR: not a directory, open '/my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/'

    at async open (node:internal/fs/promises:638:25)
    at async readFile (node:internal/fs/promises:1238:14)
    at async node_modules/rollup/dist/es/shared/node-entry.js:21005:24
    at async Queue.work (node_modules/rollup/dist/es/shared/node-entry.js:22231:32) 



[5:16:21 PM]  ERROR  Could not load /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/: ENOTDIR: not a directory, open '/my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/'

error: script "build" exited with code 1

[felixgabler]

Update & Further Debugging:

I've done some targeted debugging by adding logging to the resolveId hook within node_modules/nitropack/dist/presets/_unenv/preset-workerd.mjs (the compiled version of preset-workerd.ts).

The goal was to see exactly how the path to .../_unenv/workerd/process.mjs was being resolved just before the ENOTDIR error.

Findings:

1. Most imports resolve correctly: For the majority of modules importing process, the resolveId hook correctly identifies the path without a trailing slash:

   --- [NITRO DEBUG RELEVANT] ---
   [NITRO DEBUG] resolveId called with id: /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs
   [NITRO DEBUG]   ...imported by: /my-project/node_modules/@anthropic-ai/sdk/node_modules/node-fetch/src/utils/is.js
   [NITRO DEBUG]   -> Resolving as internal workerd path: /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs
   --- [NITRO DEBUG RELEVANT END] ---
   

2. Incorrect path originates from readable-stream: Just before the build fails, imports from the readable-stream package request the module with an incorrect trailing slash:

   --- [NITRO DEBUG RELEVANT] ---
   [NITRO DEBUG] resolveId called with id: /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/
   [NITRO DEBUG]   ...imported by: /my-project/node_modules/readable-stream/lib/internal/streams/end-of-stream.js
   [NITRO DEBUG]   -> Resolving as internal workerd path: /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/
   --- [NITRO DEBUG RELEVANT END] ---
   
   --- [NITRO DEBUG RELEVANT] ---
   [NITRO DEBUG] resolveId called with id: /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/
   [NITRO DEBUG]   ...imported by: /my-project/node_modules/readable-stream/lib/internal/streams/pipeline.js
   [NITRO DEBUG]   -> Resolving as internal workerd path: /my-project/node_modules/nitropack/dist/presets/_unenv/workerd/process.mjs/
   --- [NITRO DEBUG RELEVANT END] ---
   
   (Similar logs for destroy.js, readable.js, writable.js within readable-stream)
   

3. Build Fails: Subsequently, Rollup (or the Nitro build process) tries to load this incorrect path (.../process.mjs/) and fails with the ENOTDIR error because it's not a directory.

Conclusion:

The root cause appears to be that when using the cloudflare-pages preset, imports of the process polyfill originating specifically from the readable-stream package are incorrectly constructed with a trailing slash before they reach Nitro's workerdHybridNodeCompatPlugin. The plugin itself correctly identifies the path based on the directory, but it includes the erroneous slash already present in the ID.

This points towards an issue in how Nitro/Rollup handles the module graph or applies polyfills/aliases for readable-stream when targeting Cloudflare Pages.

Hope this helps pinpoint the issue!

[pi0]

Thank you for sharing the investigations and upstream report ❤

It seems we need to fix readable-stream but first, can you please help make a minimal reproduction? (perhaps a nitro project that uses this package)

[felixgabler]

Here is the repository that lets me repro it: https://github.com/felixgabler/cloudflare-pages-build-repro

I just need to run bun install and then bun run build and I will get the following logs:

cloudflare-pages-build-repro git:(main) ✗ bun run build                    
$ nuxt build
Nuxt 3.16.2 with Nitro 2.11.8                                                                              nuxi  8:57:08 PM
ℹ Building for Nitro preset: cloudflare-pages                                                             nuxi  8:57:09 PM
ℹ Building client...                                                                                            8:57:10 PM
ℹ vite v6.2.4 building for production...                                                                        8:57:10 PM
ℹ ✓ 127 modules transformed.                                                                                    8:57:11 PM
ℹ .nuxt/dist/client/manifest.json                   1.06 kB │ gzip:  0.30 kB                                    8:57:11 PM
ℹ .nuxt/dist/client/_nuxt/error-500.JESWioAZ.css    1.88 kB │ gzip:  0.72 kB                                    8:57:11 PM
ℹ .nuxt/dist/client/_nuxt/error-404.aNCZ2L4y.css    3.56 kB │ gzip:  1.10 kB                                    8:57:11 PM
ℹ .nuxt/dist/client/_nuxt/entry.BmwB1ty4.css       12.41 kB │ gzip:  2.57 kB                                    8:57:11 PM
ℹ .nuxt/dist/client/_nuxt/BGJX_e3L.js               3.39 kB │ gzip:  1.53 kB                                    8:57:11 PM
ℹ .nuxt/dist/client/_nuxt/DBUhDxRT.js               9.42 kB │ gzip:  3.77 kB                                    8:57:11 PM
ℹ .nuxt/dist/client/_nuxt/BPhY8Puk.js             220.37 kB │ gzip: 63.28 kB                                    8:57:11 PM
ℹ ✓ built in 822ms                                                                                              8:57:11 PM
✔ Client built in 831ms                                                                                         8:57:11 PM
ℹ Building server...                                                                                            8:57:11 PM
ℹ vite v6.2.4 building SSR bundle for production...                                                             8:57:11 PM
ℹ ✓ 52 modules transformed.                                                                                     8:57:11 PM
ℹ ✓ built in 337ms                                                                                              8:57:11 PM
✔ Server built in 342ms                                                                                         8:57:11 PM

 WARN  [cloudflare] Node.js compatibility is not enabled.                                                  nitro 8:57:11 PM

✔ Generated public dist                                                                                   nitro 8:57:11 PM
ℹ Building Nuxt Nitro server (preset: cloudflare-pages, compatibility date: 2024-11-01)                   nitro 8:57:11 PM

[nitro 8:57:12 PM]  ERROR  Error: ENOTDIR: not a directory, stat '/Users/felixgabler/cloudflare-pages-build-repro/node_modules/unenv/dist/runtime/node/process.mjs/'


undefined


[8:57:12 PM]  ERROR  ENOTDIR: not a directory, stat '/Users/felixgabler/cloudflare-pages-build-repro/node_modules/unenv/dist/runtime/node/process.mjs/'

   



[8:57:12 PM]  ERROR  ENOTDIR: not a directory, stat '/Users/felixgabler/cloudflare-pages-build-repro/node_modules/unenv/dist/runtime/node/process.mjs/'

error: script "build" exited with code 1

[felixgabler]

Further investigation confirms this ENOTDIR error originates from an incompatibility between readable-stream and Nitro's polyfilling strategy for the cloudflare-pages preset.

Specifically, readable-stream uses require('process/') (with a trailing slash), which seems to conflict with how unenv provides the process polyfill in this environment, leading to the build error when the bundler tries to stat the path. This pattern is a known issue in readable-stream when used with modern bundlers and non-Node environments (see readable-stream#539, readable-stream#540, readable-stream#553). A potential fix (readable-stream#543) is currently stalled.

I can make my build run through by manually patching node_modules/readable-stream to replace instances of require('process/') with require('process') (and similarly for require('string_decoder/')). This at least unblocks my experimentation with Nuxt Hub. However, it obviously does not fix the core issue.

@pi0 given that the issues and PR in readable-stream don't move forward, do you think it makes sense to fix this in Nitro or unenv somewhere? Or what would be your proposed way forward?

[pi0]

Thank you for the reproduction ❤

This is a workaround:

export default defineNuxtConfig({
  nitro: {
    preset: "cloudflare-pages",
    // Recommended for better compatibility
    cloudflare: {
      deployConfig: true,
      nodeCompat: true,
    },
    // https://github.com/nitrojs/nitro/issues/3271
    unenv: {
      alias: {
        'string_decoder/': 'node:string_decoder',
        'process/': 'node:process'
      }
    }
  },
});

If worked, can you please open a PR to update here