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Troubleshooting

See Rollup's troubleshooting guide for more information too.

If the suggestions here don't work, please try posting questions on GitHub Discussions or in the #help channel of Vite Land Discord.

CJS

Vite CJS Node API deprecated

The CJS build of Vite's Node API is deprecated and will be removed in Vite 6. See the GitHub discussion for more context. You should update your files or frameworks to import the ESM build of Vite instead.

In a basic Vite project, make sure:

  1. The vite.config.js file content is using the ESM syntax.
  2. The closest package.json file has "type": "module", or use the .mjs/.mts extension, e.g. vite.config.mjs or vite.config.mts.

For other projects, there are a few general approaches:

  • Configure ESM as default, opt-in to CJS if needed: Add "type": "module" in the project package.json. All *.js files are now interpreted as ESM and needs to use the ESM syntax. You can rename a file with the .cjs extension to keep using CJS instead.
  • Keep CJS as default, opt-in to ESM if needed: If the project package.json does not have "type": "module", all *.js files are interpreted as CJS. You can rename a file with the .mjs extension to use ESM instead.
  • Dynamically import Vite: If you need to keep using CJS, you can dynamically import Vite using import('vite') instead. This requires your code to be written in an async context, but should still be manageable as Vite's API is mostly asynchronous.

If you're unsure where the warning is coming from, you can run your script with the VITE_CJS_TRACE=true flag to log the stack trace:

bash
VITE_CJS_TRACE=true vite dev

If you'd like to temporarily ignore the warning, you can run your script with the VITE_CJS_IGNORE_WARNING=true flag:

bash
VITE_CJS_IGNORE_WARNING=true vite dev

Note that postcss config files does not support ESM + TypeScript (.mts or .ts in "type": "module") yet. If you have postcss configs with .ts and added "type": "module" to package.json, you'll also need to rename the postcss config to use .cts.

CLI

Error: Cannot find module 'C:\foo\bar&baz\vite\bin\vite.js'

The path to your project folder may include &, which doesn't work with npm on Windows (npm/cmd-shim#45).

You will need to either:

  • Switch to another package manager (e.g. pnpm, yarn)
  • Remove & from the path to your project

Config

This package is ESM only

When importing a ESM only package by require, the following error happens.

Failed to resolve "foo". This package is ESM only but it was tried to load by require.

"foo" resolved to an ESM file. ESM file cannot be loaded by require.

ESM files cannot be loaded by require.

We recommend converting your config to ESM by either:

  • adding "type": "module" to the nearest package.json
  • renaming vite.config.js/vite.config.ts to vite.config.mjs/vite.config.mts

Dev Server

Requests are stalled forever

If you are using Linux, file descriptor limits and inotify limits may be causing the issue. As Vite does not bundle most of the files, browsers may request many files which require many file descriptors, going over the limit.

To solve this:

  • Increase file descriptor limit by ulimit

    shell
    # Check current limit
    $ ulimit -Sn
    # Change limit (temporary)
    $ ulimit -Sn 10000 # You might need to change the hard limit too
    # Restart your browser
  • Increase the following inotify related limits by sysctl

    shell
    # Check current limits
    $ sysctl fs.inotify
    # Change limits (temporary)
    $ sudo sysctl fs.inotify.max_queued_events=16384
    $ sudo sysctl fs.inotify.max_user_instances=8192
    $ sudo sysctl fs.inotify.max_user_watches=524288

If the above steps don't work, you can try adding DefaultLimitNOFILE=65536 as an un-commented config to the following files:

  • /etc/systemd/system.conf
  • /etc/systemd/user.conf

For Ubuntu Linux, you may need to add the line * - nofile 65536 to the file /etc/security/limits.conf instead of updating systemd config files.

Note that these settings persist but a restart is required.

Network requests stop loading

When using a self-signed SSL certificate, Chrome ignores all caching directives and reloads the content. Vite relies on these caching directives.

To resolve the problem use a trusted SSL cert.

See: Cache problems, Chrome issue

macOS

You can install a trusted cert via the CLI with this command:

security add-trusted-cert -d -r trustRoot -k ~/Library/Keychains/login.keychain-db your-cert.cer

Or, by importing it into the Keychain Access app and updating the trust of your cert to "Always Trust."

431 Request Header Fields Too Large

When the server / WebSocket server receives a large HTTP header, the request will be dropped and the following warning will be shown.

Server responded with status code 431. See https://vitejs.dev/guide/troubleshooting.html#_431-request-header-fields-too-large.

This is because Node.js limits request header size to mitigate CVE-2018-12121.

To avoid this, try to reduce your request header size. For example, if the cookie is long, delete it. Or you can use --max-http-header-size to change max header size.

HMR

Vite detects a file change but the HMR is not working

You may be importing a file with a different case. For example, src/foo.js exists and src/bar.js contains:

js
import './Foo.js' // should be './foo.js'

Related issue: #964

Vite does not detect a file change

If you are running Vite with WSL2, Vite cannot watch file changes in some conditions. See server.watch option.

A full reload happens instead of HMR

If HMR is not handled by Vite or a plugin, a full reload will happen as it's the only way to refresh the state.

If HMR is handled but it is within a circular dependency, a full reload will also happen to recover the execution order. To solve this, try breaking the loop. You can run vite --debug hmr to log the circular dependency path if a file change triggered it.

Build

Built file does not work because of CORS error

If the HTML file output was opened with file protocol, the scripts won't run with the following error.

Access to script at 'file:///foo/bar.js' from origin 'null' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, isolated-app, chrome-extension, chrome, https, chrome-untrusted.

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at file:///foo/bar.js. (Reason: CORS request not http).

See Reason: CORS request not HTTP - HTTP | MDN for more information about why this happens.

You will need to access the file with http protocol. The easiest way to achieve this is to run npx vite preview.

Optimized Dependencies

Outdated pre-bundled deps when linking to a local package

The hash key used to invalidate optimized dependencies depend on the package lock contents, the patches applied to dependencies, and the options in the Vite config file that affects the bundling of node modules. This means that Vite will detect when a dependency is overridden using a feature as npm overrides, and re-bundle your dependencies on the next server start. Vite won't invalidate the dependencies when you use a feature like npm link. In case you link or unlink a dependency, you'll need to force re-optimization on the next server start by using vite --force. We recommend using overrides instead, which are supported now by every package manager (see also pnpm overrides and yarn resolutions).

Performance bottlenecks

If you suffer any application performance bottlenecks resulting in slow load times, you can start the built-in Node.js inspector with your Vite dev server or when building your application to create the CPU profile:

bash
vite --profile --open
bash
vite build --profile

Vite Dev Server

Once your application is opened in the browser, just await finish loading it and then go back to the terminal and press p key (will stop the Node.js inspector) then press q key to stop the dev server.

Node.js inspector will generate vite-profile-0.cpuprofile in the root folder, go to https://www.speedscope.app/, and upload the CPU profile using the BROWSE button to inspect the result.

You can install vite-plugin-inspect, which lets you inspect the intermediate state of Vite plugins and can also help you to identify which plugins or middlewares are the bottleneck in your applications. The plugin can be used in both dev and build modes. Check the readme file for more details.

Others

Module externalized for browser compatibility

When you use a Node.js module in the browser, Vite will output the following warning.

Module "fs" has been externalized for browser compatibility. Cannot access "fs.readFile" in client code.

This is because Vite does not automatically polyfill Node.js modules.

We recommend avoiding Node.js modules for browser code to reduce the bundle size, although you can add polyfills manually. If the module is imported from a third-party library (that's meant to be used in the browser), it's advised to report the issue to the respective library.

Syntax Error / Type Error happens

Vite cannot handle and does not support code that only runs on non-strict mode (sloppy mode). This is because Vite uses ESM and it is always strict mode inside ESM.

For example, you might see these errors.

[ERROR] With statements cannot be used with the "esm" output format due to strict mode

TypeError: Cannot create property 'foo' on boolean 'false'

If these code are used inside dependencies, you could use patch-package (or yarn patch or pnpm patch) for an escape hatch.

Browser extensions

Some browser extensions (like ad-blockers) may prevent the Vite client from sending requests to the Vite dev server. You may see a white screen without logged errors in this case. Try disabling extensions if you have this issue.

If there's a cross drive links in your project on Windows, Vite may not work.

An example of cross drive links are:

  • a virtual drive linked to a folder by subst command
  • a symlink/junction to a different drive by mklink command (e.g. Yarn global cache)

Related issue: #10802

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