重現方式：

> npm install and then yarn dev:ssr
錯誤訊息：

> Compiled successfully.
** Anqular Universal Live Development Server is Listening on http://localhost:4201,open your browser on http://localhost:4201 **
ERROR Error: Uncaught (in promise): Error: RouterModule.forRoot() called twice. Lazy Loaded modules should use RouterModule.forChild() instead.
Error: RouterModule.forRoot() called twice. Lazy Loaded modules should use RouterModule.forChild() instead
	at Object.provideForRootGuard [as useFactory] (C:\Code\sony20210526\dist\spartcusstore-server\main. js:115752:15)
	at Object. factory (C:\Code\sony20210526\dist\spartacusstore-server\main.js:64140:28)
	at R3Injector.hydrate (C:\Code\sony20210526\dist\spartacusstore-server\main.js:64007:63)
	at R3Injector.get (C:\Code\sony20210526\dist\spartacusstore-server\main.js:63757:33)
	at injectInjectorOnly (C:\Code\sony20210526\dist\spartacusstore-server\main.js:49630:33)
	at Module. Dinject (C:\Code\sony20210526\dist\spartacusstore-server\main.js:49640:57)

![](https://img-blog.csdnimg.cn/img_convert/67f193f7ee73d61291bd0758f32c8008.png)

SAP Spartacus 版本號： 2.1.7

# 分析

出問題的 homeModule：
![](https://img-blog.csdnimg.cn/img_convert/5c956ecc36227efb4a4ca52906313aed.png)

> HomeModule is importing B2cStorefrontModule, which shouldn't be imported twice in any scenario, especially shouldn't be lazy-loaded.

B2bStorefrontModule 不應該被載入兩次，也不應該以懶載入的方式被載入。

但事實上，該 module 被重複載入了多次：

![](https://img-blog.csdnimg.cn/img_convert/86290f504ec6ce0d07719b149e7d0b88.png)

> Any lazy-loaded module should only import the most necessary modules to avoid additional performance impact, and it's especially important for recipe modules like B2cStorefrontModule (the complete b2c storefront recipe).

Custom Module 裡如果想提供配置，建議使用[如下方式](https://sap.github.io/spartacus-docs/global-configuration-in-spartacus):

> `ConfigModule.withConfig()` or `provideConfig` utility/#page-title).

如果使用者有大量的自定義邏輯，不推薦使用形如 B2cStorefrontModule 的 recipe module, 而是 building individually tailored storefronts by importing only modules that are needed.

並且，b2cStorefrontModule 在 3.x 版本被設定為 deprecated 狀態，並且將來會被移除, in favor of a standardized [reference structure](https://sap.github.io/spartacus-docs/reference-app-structure/).

SAP Spartacus RouterModule.forRoot() called twice 的錯誤訊息

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