InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request. Your application is running in Production mode, so make sure it has been publ

Mendenzon Tatis Rosario 20 Reputation points

This happened before with another application of mine which I was able to fix by removing the use redirect. However, this time it seems to be more complex, I am using dotNet 7 for the application and React for the front end all my checks are successful on github actions but the internal server error persists with the Spa not finding the indix.html. I also tried using the useFallBack(index.html) but the error persist.

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Accepted answer
  1. JasonPan - MSFT 4,201 Reputation points Microsoft Vendor

    Hi @Mendenzon Tatis Rosario,

    For SPA projects, usually the front-end project is Angular/React/Vue, and the back-end project is ASP.NET Core API.

    Therefore, in the ASP.NET Core API, you need to use app.UseSpa or UseStaticFiles to allow static resource files to be read, and then the front-end project of the SPA needs to be included in the compilation process. This ensures that the index.html file can be found using useFallBack as an entry.

    Sample settings

        <!-- Don't publish the SPA source files, but do show them in the project files list -->
        <Content Remove="$(SpaRoot)**" />
        <None Remove="$(SpaRoot)**" />
        <None Include="$(SpaRoot)**" Exclude="$(SpaRoot)node_modules\**" />
        <Content Include="ClientApp\dist\**">

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    Best regards,


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