#Build

This page collects build-time error codes and common troubleshooting guidance.

#Error Codes

• BUILD-001
• BUILD-002

#BUILD-001

Failed to find expose module.

• Error Code: BUILD-001

#Reasons

Failed to find the Expose module resource.

There are two possible reasons:

1. The exposeModules file path configured in exposes is incorrect and points to a non-existing path.
2. When using Next.js or other frameworks with built-in webpack, the webpack path used by MF does not match the framework's webpack path.

#Solutions

1. Check whether the module file path in exposes is correct, paying attention to case sensitivity.
2. Check whether FEDERATION_WEBPACK_PATH matches the webpack path used by the framework. If not, verify dependencies are installed correctly or set process.env.FEDERATION_WEBPACK_PATH to the actual webpack path.

#BUILD-002

PublicPath is required in prod mode.

• Error Code: BUILD-002

#Reasons

When building an Rspress producer, the project must set publicPath, otherwise it cannot be loaded normally by other consumers.

#Solutions

Set publicPath via one of the following methods:

• Set builderConfig.output.assetPrefix in rspress.config.ts

export default {
  builderConfig: {
    output: {
      assetPrefix: 'https://module-federation.io/',
    }
  }
}

• Set builderConfig.tools.rspack in rspress.config.js

export default {
  builderConfig: {
    tools: {
      rspack: (config)=>{
        config.output.publicPath = 'https://module-federation.io/';
      },
    }
  }
}

#Common Issues (No Error Code)

#CORS warn

When exposes is set in the project, it will be regarded as a producer. To ensure that the producer resources can be loaded normally by consumers, @module-federation/modern-js and @module-federation/rsbuild-plugin will set Access-Control-Allow-Origin to * and issue a warning at the same time.

#Solutions

• [Modern.js]: Set devServer.headers value to the specified domain whitelist instead of *

• [Rsbuild]: Set server.cors.origin value to the specified domain whitelist instead of *

#Multiple assets emit different content to the same filename mf-manifest.json

#Reason

In Rspack 1.6.0-beta.0, we ported the manifest implementation to Rust. Upgrading Rspack without upgrading the MF-related packages will cause this error.

#Solution

Upgrade the @module-federation scoped npm package to version 0.21.0 or later.