net6.0-windows 
namespace Microsoft.AspNetCore.Builder
{
    [Obsolete("Use Microsoft.AspNetCore.SpaServices.Extensions")]
    public static class SpaRouteExtensions
    {
        public static void MapSpaFallbackRoute(this IRouteBuilder routeBuilder, string name, string templatePrefix, object defaults, object constraints = null, object dataTokens = null);
    }
}
.NET
5.06.07.08.09.010.0
.NET Core
2.02.12.23.1
Information specific to net6.0
Assembly

Microsoft.AspNetCore.SpaServices , Version=3.1.32.0, PublicKeyToken=adb9793829ddae60

Referencing

Your project needs a package reference to Microsoft.AspNetCore.SpaServices.

Package Microsoft.AspNetCore.SpaServices (3.1.32) netcoreapp3.1
Platform Restrictions

This API is supported on all platforms.

  • Built-in API
  • Package-provided API