A library to run WebForms apps on ASP.NET Core. This library provides a port of the System.Web libraries of .NET Framework to .NET 8. With this library, you can run WebForms websites directly in ASP.NET Core.

If you have a WebForms project you want to convert to NET Core, proceed as follows:

First convert your Project to a SDK Project. For the moment, please also keep the old non SDK style project, as WebFormsForCore does not yet properly support generation of the Designer.cs files from aspx. Conversion can be done easiest by using a converter like the migrate-2019 tool. To install that tool, run dotnet tool install --global Project2015To2017.Migrate2019.Tool. Then go to the directory of your solution and run dotnet migrate-2019 wizard to convert your solution to an SDK project. After conversion change the target framework of your project to net8.0. You might also keep net48, in order to dual run your project with NET Framework & NET Core. Change the OutputPath for net8.0 to bin_dotnet:

<PropertyGroup>
    <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
    <AppendRuntimeIdentifierToOutputPath>false</AppendRuntimeIdentifierToOutputPath>
</PropertyGroup>

<PropertyGroup Condition="'$(TargetFramework)' != 'net48'">
    <OutputType>Exe</OutputType>
    <OutputPath>bin_dotnet</OutputPath>
    <StartupObject>Program</StartupObject>
</PropertyGroup>

<PropertyGroup Condition="'$(TargetFramework)' == 'net48'">
    <OutputType>Library</OutputType>
    <OutputPath>bin</OutputPath>
</PropertyGroup>

Then, for net8.0, import the WebFormsForCore packages like so:

<ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
    <PackageReference Include="EstrellasDeEsperanza.WebFormsForCore.Web" Version="1.0.0" />
</ItemGroup>

Remove the old Reference references or put them in a condition only for net48.

If your project also needs System.Web.Extensions or System.Web.Optimization import the corresponding packages also, like EstrellasDeEsperanza.WebFormsForCore.Web.Extensions or EstrellasDeEsperanza.WebFormsForCore.Web.Optimization etc. The following packages are available:

• System.Configuration: EstrellasDeEsperanza.WebFormsForCore.Configuration
• System.Web: EstrellasDeEsperanza.WebFormsForCore.Web
• System.Web.Services: EstrellasDeEsperanza.WebFormsForCore.Web.Services
• System.Web.Extensions: EstrellasDeEsperanza.WebFormsForCore.Web.Extensions
• System.Web.Optimization: EstrellasDeEsperanza.WebFormsForCore.Web.Optimization
• Microsoft.AspNet.Web.Optimization.WebForms: EstrellasDeEsperanza.WebFormsForCore.Web.Optimization.WebForms
• WebGrease: EstrellasDeEsperanza.WebFormsForCore.WebGrease

Finally configure ASP-NET Core to use WebForms in the initialization code Program.cs like so:

#if NETCOREAPP

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;

public class Program
{

	public static void Main(string[] args)
	{
		var builder = WebApplication.CreateBuilder(args);

		// Add services to the container.
		builder.Services.AddRazorPages();
		builder.Services.AddControllersWithViews();

		var app = builder.Build();

		app.UseStaticFiles();

		//app.UseAuthorization();

		app.UseWebForms();

		app.MapDefaultControllerRoute();
			
		app.Run();

	}
}
#endif

Currently there might be some conflicts with the packages System.Web.dll & System.Configuration.ConfigurationManager.dll, since WebFormsForCore replaces those dll's. In order to prevent import of the old dll's include the following in your csproj:

<Target Name="ChangeAliasesOfNugetRefs" BeforeTargets="FindReferenceAssembliesForReferences;ResolveReferences">
    <ItemGroup>
        <!-- Do not import System.Configuration.ConfigurationManager version 8 -->
        <ReferencePath Remove="%(Identity)" Condition="'%(FileName)' == 'System.Configuration.ConfigurationManager' AND $([System.Text.RegularExpressions.Regex]::IsMatch(%(Identity),'\\8.0.0\\'))" />
        <!-- Do not import System.Web -->
        <ReferencePath Remove="%(Identity)" Condition="'%(FileName)' == 'System.Web' AND $([System.Text.RegularExpressions.Regex]::IsMatch(%(Identity),'\\dotnet\\'))" />
    </ItemGroup>
</Target>