Asp.Net Core 2.0 Web Application Static Files Gives 404

I had the problem during development.I used the overloaded method of UseStaticFiles to set the option ServeUnknownFileTypes to true.

public void Configure(IApplicationBuilder app, IHostingEnvironment env) {    app.UseDeveloperExceptionPage()        .UseSession()        .UseStaticFiles(new StaticFileOptions        {            ServeUnknownFileTypes = true,        })        .UseDirectoryBrowser()        .UseRequestLocalization()        .UseMvcWithDefaultRoute();}

I am not sure, but it looks like your extension is denied by IIS settings to access directly as a static resource. Please, try this for the web.config:

<configuration>    <system.webServer>        <security>           <requestFiltering>               <fileExtensions>                 <add fileExtension=".appinstaller" allowed="true" />               </fileExtensions>          </requestFiltering>        </security>     </system.webServer> </configuration> 

Also check request filtering. See more information:How to deny access to a specific file name extension

This answer might come in late, but in my case the solution was in my IIS settings.JavaScript file extension (.js) is set to False in Allowed column of Request Filtering.Removing js file from Request Filtering solved this case for me.