Replace Upgrade Assistant content with GitHub Copilot app modernization guidance (#36437)

* Initial plan

* Replace Upgrade Assistant content with GitHub Copilot app modernization guidance

Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>

* Update upgrade process for supporting libraries

Added a reference to GitHub Copilot app modernization for library upgrades.

* Enhance migration instructions with GitHub Copilot reference

Added a reference to GitHub Copilot app modernization for assistance in identifying project changes during migration.

* Update ms.date for ASP.NET Core guide

* Update ms.date date in start.md

* Update tooling.md

* Revise tooling documentation for ASP.NET migration

Updated the tooling documentation to emphasize the use of the GitHub Copilot app modernization for migrating ASP.NET Framework applications to ASP.NET Core, replacing mentions of the deprecated .NET Upgrade Assistant.

* Apply suggestions from code review

* Fix metadata ordering, broken link, and See also URLs per review feedback

Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>

* Revise tooling.md for .NET Upgrade Assistant deprecation

Updated the tooling documentation to reflect the deprecation of .NET Upgrade Assistant and added a new quickstart link for GitHub Copilot app modernization.

* Document GitHub Copilot app modernization for migration

Added information about the GitHub Copilot app modernization extension for upgrading ASP.NET Framework applications to ASP.NET Core.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>
Co-authored-by: Wade Pickett <wpickett@microsoft.com>

Author: Copilot

aspnetcore/migration/fx-to-core/index.md

@@ -3,7 +3,7 @@ title: Migrate from ASP.NET Framework to ASP.NET Core
 author: wadepickett
 description: Your complete guide to migrating ASP.NET Framework applications to ASP.NET Core, with practical approaches and step-by-step guidance.
 ms.author: wpickett
-ms.date: 11/10/2025
+ms.date: 12/04/2025
 uid: migration/fx-to-core/index
 ---
 # Migrate from ASP.NET Framework to ASP.NET Core
@@ -90,4 +90,4 @@ Incremental migration is an implementation of the Strangler Fig pattern and is b
 
 ## In place migration
 
-In place migration can work for sufficiently small applications. If possible, this allows for a quick replacement of the application. However, small issues may be compounded if you decide to do an in place migration. See <xref:migration/fx-to-core/tooling> to learn how Upgrade Assistant can help with an in place migration.
+In place migration can work for sufficiently small applications. If possible, this allows for a quick replacement of the application. However, small issues may be compounded if you decide to do an in place migration. See <xref:migration/fx-to-core/tooling> for information on migration tooling options.

aspnetcore/migration/fx-to-core/start.md

@@ -4,7 +4,7 @@ description: Get started with incremental ASP.NET to ASP.NET Core migration
 author: wadepickett
 ms.author: wpickett
 monikerRange: '>= aspnetcore-6.0'
-ms.date: 07/17/2025
+ms.date: 12/04/2025
 ms.topic: article
 uid: migration/fx-to-core/start
 ---
@@ -147,15 +147,15 @@ Depending on your application, you may also need to address:
 
 **Upgrade process for each library:**
 
-If you have supporting libraries in your solution that you will need to use for the routes you're migrating, they should be upgraded to .NET Standard 2.0, if possible. [Upgrade Assistant](https://github.com/dotnet/upgrade-assistant) is a great tool for this. If libraries are unable to target .NET Standard, you can target .NET 8 or later either along with the .NET Framework target in the original project or in a new project alongside the original.
+If you have supporting libraries in your solution that you will need to use for the routes you're migrating, they should be upgraded to .NET Standard 2.0, if possible. [GitHub Copilot app modernization](/dotnet/core/porting/github-copilot-app-modernization/overview) can help you with this. If libraries are unable to target .NET Standard, you can target .NET 8 or later either along with the .NET Framework target in the original project or in a new project alongside the original.
 
 The [System.Web adapters](~/migration/fx-to-core/inc/systemweb-adapters.md) can be used in these libraries to enable support for <xref:System.Web.HttpContext> usage in class libraries. In order to enable <xref:System.Web.HttpContext> usage in a library:
 
 1. Remove reference to `System.Web` in the project file
 2. Add the `Microsoft.AspNetCore.SystemWebAdapters` package
 3. Enable multi-targeting and add a .NET 8 target or later, or convert the project to .NET Standard 2.0.
 
-This step may require a number of projects to change depending on your solution structure and which routes you're migrating. Upgrade Assistant can help you identify which ones need to change and automate a number of steps in the process.
+This step may require a number of projects to change depending on your solution structure and which routes you're migrating. [GitHub Copilot app modernization](/dotnet/core/porting/github-copilot-app-modernization/overview) can help you identify which ones need to change and automate a number of steps in the process.
 
 
 ## Next Steps

aspnetcore/migration/fx-to-core/tooling.md

@@ -1,47 +1,25 @@
 ---
 title: Learn to upgrade from ASP.NET MVC, Web API, and Web Forms to ASP.NET Core
-description: Learn how to upgrade ASP.NET Framework MVC, Web API, or Web Forms projects to ASP.NET Core using migration tooling
+ai-usage: ai-assisted
 author: wadepickett
+description: Learn how to upgrade ASP.NET Framework MVC, Web API, or Web Forms projects to ASP.NET Core using migration tooling.
 ms.author: wpickett
-ms.date: 07/17/2025
+ms.date: 12/04/2025
 uid: migration/fx-to-core/tooling
 ---
 # Use tooling to help migrate ASP.NET Framework to ASP.NET Core
 
-This article shows how to upgrade ASP.NET Framework applications (MVC, Web API, and Web Forms) to ASP.NET Core using the Visual Studio [.NET Upgrade Assistant](https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.upgradeassistant) and the [incremental update](xref:migration/fx-to-core/index) approach.
+## The GitHub Copilot app modernization
 
+To upgrade ASP.NET Framework applications (MVC, Web API, and Web Forms) to ASP.NET Core, use the [GitHub Copilot app modernization Visual Studio extension](/dotnet/core/porting/github-copilot-app-modernization/overview).
 
-   > [!WARNING]
-   > There is a Copilot-enabled tool for staying current on modern .NET, but is not currently enabled for migrating ASP.NET Framework to ASP.NET Core. Please see the documentation for [GitHub Copilot app modernization - Upgrade for .NET](/dotnet/core/porting/github-copilot-app-modernization-overview) for details.
-
-## Prerequisites
+The GitHub Copilot app modernization agent is a Visual Studio extension that leverages AI to simplify the process of upgrading legacy .NET applications. By integrating with GitHub Copilot Chat, this tool analyzes your solution to generate upgrade plans and assists in rewriting code to support ASP.NET Core. It streamlines the migration workflow by reducing manual effort, identifying dependencies, and providing interactive, automated guidance for modernizing your codebase. To learn how to upgrade your ASP.NET apps using the recommended tooling, see [How to upgrade a .NET app with GitHub Copilot app modernization](/dotnet/core/porting/github-copilot-app-modernization/how-to-upgrade-with-github-copilot).
 
 If your .NET Framework project has supporting libraries in the solution that are required, they should be upgraded to .NET Standard 2.0, if possible. For more information, see [Upgrade supporting libraries](xref:migration/fx-to-core/start#upgrade-supporting-libraries).
 
+> [!IMPORTANT]
+> .NET Upgrade Assistant is officially deprecated. Use the [GitHub Copilot app modernization chat agent](/dotnet/core/porting/github-copilot-app-modernization/overview) instead, which is included with Visual Studio 2026 and Visual Studio 2022 17.14.16 or later. This agent analyzes your projects and dependencies, produces a step-by-step migration plan with targeted recommendations and automated code fixes, and commits each change so you can validate or roll back. It automates common porting tasks—updating project files, replacing deprecated APIs, and resolving build issues—so you can modernize faster with less manual effort.
 
-1. Install the [.NET Upgrade Assistant](https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.upgradeassistant) Visual Studio extension.
-1. Open your ASP.NET Framework solution in Visual Studio.
-1. In **Solution Explorer**, right click on the project to upgrade and select **Upgrade**. Select **Side-by-side incremental project upgrade**, which is the only upgrade option.
-1. For the upgrade target, select **New project**.
-1. Name the project and select the most appropriate template. If your solution includes multiple project types, you may add the required services later:
-
-   > [!NOTE]
-   > **For MVC projects:** Select **ASP.NET Core MVC** template.
-   > 
-   > **For Web API projects:** Select **ASP.NET Core Web API** template.
-   > 
-   > **For MVC + Web API projects:** Select **ASP.NET Core MVC** template.
-   > 
-   > **For Web Forms projects:** Select **ASP.NET Core** template.
-
-1. Select **Next**
-1. Select the target framework version and then select **Next**. For more information, see [.NET and .NET Core Support Policy](https://dotnet.microsoft.com/platform/support/policy/dotnet-core).
-
-   > [!NOTE]
-   > **For Web Forms projects:** Select **Done** instead of **Next**, then proceed to step 9.
-
-1. Review the **Summary of changes**, then select **Finish**.
-1. The **Summary** step displays **`<Framework Project>` is now connected to `<Framework ProjectCore>` via Yarp proxy.**
+## See also
 
-   > [!NOTE]
-   > **For MVC and Web API projects:** The summary includes a pie chart showing the migrated endpoints. Select **Upgrade Controller** and then select a controller to upgrade. Select the component to upgrade, then select **Upgrade selection**.
+* [Quickstart: Assess and migrate a .NET project with GitHub Copilot app modernization for .NET](/dotnet/azure/migration/appmod/quickstart)