Migrating from ASP.NET 5 RC1 to ASP.NET Core 1.0

By Cesar Blum Silveira, Rachel Appel, Rick Anderson

ASP.NET 5 RC1 apps were based on the .NET Execution Environment (DNX) and made use of DNX specific features. ASP.NET Core 1.0 is based on .NET Core, so you must first migrate your application to the new .NET Core project model. See migrating from DNX to .NET Core CLI for more information.

See the following resources for a list of some of the most significant changes, announcements and migrations information:

Update Target Framework Monikers (TFMs)

If your app targeted dnx451 or dnxcore50 in the frameworks section of project.json, you must make the following changes:

dnx451 net451
dnxcore50 netcoreapp1.0

.NET Core apps must add a dependency to the Microsoft.NETCore.App package:

"dependencies": {
  "Microsoft.NETCore.App": {
    "version": "1.0.0",
    "type": "platform"

Namespace and package ID changes

  • ASP.NET 5 has been renamed to ASP.NET Core 1.0
  • ASP.NET MVC and Identity are now part of ASP.NET Core
  • ASP.NET MVC 6 is now ASP.NET Core MVC
  • ASP.NET Identity 3 is now ASP.NET Core Identity
  • ASP.NET Core 1.0 package versions are 1.0.0
  • ASP.NET Core 1.0 tool package versions are 1.0.0-preview2-final

Namespace and package name changes:

ASP.NET 5 RC1 ASP.NET Core 1.0
Microsoft.AspNet.* Microsoft.AspNetCore.*
EntityFramework.* Microsoft.EntityFrameworkCore.*
Microsoft.Data.Entity.* Microsoft.EntityFrameworkCore.*

The EntityFramework.Commands package is no longer available. The ef command is now available as a tool in the Microsoft.EntityFrameworkCore.Tools package.

The following packages have been renamed:

ASP.NET 5 RC1 ASP.NET Core 1.0
EntityFramework.MicrosoftSqlServer Microsoft.EntityFrameworkCore.SqlServer
Microsoft.AspNet.Diagnostics.Entity Microsoft.AspNetCore.Dianostics.EntityFrameworkCore
Microsoft.AspNet.Identity.EntityFramework Microsoft.AspNetCore.Identity.EntityFrameworkCore
Microsoft.AspNet.Tooling.Razor Microsoft.AspNetCore.Razor.Tools

Commands and tools

The commands section of the project.json file is no longer supported. Use dotnet run or dotnet <DLL name> instead.

.NET Core CLI has introduced the concept of tools. project.json now supports a tools section where packages containing tools can be specified. Some important functionality for ASP.NET Core 1.0 applications has been moved to tools.

See .NET Core CLI extensibility model for more information on .NET Core CLI tools.

Publishing to IIS

IIS publishing is now provided by the publish-iis tool in the Microsoft.AspNetCore.Server.IISIntegration.Tools package. If you intend to run your app behind IIS, add the publish-iis tool to your project.json:

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"

The publish-iis tool is commonly used in the postpublish script in project.json:

  "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]

Entity Framework commands

The ef tool is now provided in the Microsoft.EntityFrameworkCore.Tools package:

  "tools": {
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"

For more information, see .NET Core CLI.

Razor tools

Razor tooling is now provided in the Microsoft.AspNetCore.Razor.Tools package:

  "tools": {
    "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview2-final"

SQL cache tool

The sqlservercache command, formerly provided by the Microsoft.Extensions.Caching.SqlConfig package, has been replaced by the sql-cache tool, available through the Microsoft.Extensions.Caching.SqlConfig.Tools package:

  "tools": {
    "Microsoft.Extensions.Caching.SqlConfig.Tools": "1.0.0-preview2-final"

User secrets manager

The user-secret command, formerly provided by the Microsoft.Extensions.SecretManager package, has been replaced by the user-secrets tool, available through the Microsoft.Extensions.SecretManager.Tools package:

  "tools": {
    "Microsoft.Extensions.SecretManager.Tools": "1.0.0-preview2-final"

File watcher

The watch command, formerly provided by the Microsoft.Dnx.Watcher package, has been replaced by the watch tool, available through the Microsoft.DotNet.Watcher.Tools package:

  "tools": {
    "Microsoft.DotNet.Watcher.Tools": "1.0.0-preview2-final"

For more information on the file watcher, see Dotnet watch in Tutorials.


Creating the web application host

ASP.NET Core 1.0 apps are console apps; you must define an entry point for your app that sets up a web host and runs it. Below is an example from the startup code for one of the Web Application templates in Visual Studio:

public class Program
    public static void Main(string[] args)
        var host = new WebHostBuilder()


You must add the emitEntryPoint to the buildOptions section of your application’s project.json:

  "buildOptions": {
    "emitEntryPoint": true

Class and interface renames

All classes and interfaces prefixed with WebApplication have been renamed to start with WebHost:

ASP.NET 5 RC1 ASP.NET Core 1.0
IWebApplicationBuilder IWebHostBuilder
WebApplicationBuilder WebHostBuilder
IWebApplication IWebHost
WebApplication WebHost
WebApplicationOptions WebHostOptions
WebApplicationDefaults WebHostDefaults
WebApplicationService WebHostService
WebApplicationConfiguration WebHostConfiguration

Content root and web root

The application base path is now called the content root.

The web root of your application is no longer specified in your project.json file. It is defined when setting up the web host and defaults to wwwroot. Call the UseWebRoot extension method to specify a different web root folder. Alternatively, you can specify the web root folder in configuration and call the UseConfiguration extension method.

Server address binding

The server addresses that your application listens on can be specified using the UseUrls extension method or through configuration.

Specifying only a port number as a binding address is no longer supported. The default binding address is http://localhost:5000

Hosting configuration

The UseDefaultHostingConfiguration method is no longer available. The only configuration values read by default by WebHostBuilder are those specified in environment variables prefixed with ASPNETCORE_*. All other configuration sources must now be added explicitly to an IConfigurationBuilder instance. See Configuration for more information.

The environment key is set with the ASPNETCORE_ENVIRONMENT environment variable. ASPNET_ENV and Hosting:Environment are still supported, but generate a deprecated message warning.

Hosting service changes

Dependency injection code that uses IApplicationEnvironment must now use IHostingEnvironment. For example, in your Startup class, change:

public Startup(IApplicationEnvironment applicationEnvironment)


public Startup(IHostingEnvironment hostingEnvironment)


Kestrel configuration has changed. This GitHub announcement outlines the changes you must make to configure Kestrel if you are not using default settings.

Controller and action results renamed

The following Controller methods have been renamed and moved to ControllerBase:

ASP.NET 5 RC1 ASP.NET Core 1.0
HttpUnauthorized Unauthorized
HttpNotFound (and its overloads) NotFound
HttpBadRequest (and its overloads) BadRequest

The following action result types have also been renamed:

ASP.NET 5 RC1 ASP.NET Core 1.0
Microsoft.AspNet.Mvc.HttpOkObjectResult Microsoft.AspNetCore.Mvc.OkObjectResult
Microsoft.AspNet.Mvc.HttpOkResult Microsoft.AspNetCore.Mvc.OkResult
Microsoft.AspNet.Mvc.HttpNotFoundObjectResult Microsoft.AspNetCore.Mvc.NotFoundObjectResult
Microsoft.AspNet.Mvc.HttpNotFoundResult Microsoft.AspNetCore.Mvc.NotFoundResult
Microsoft.AspNet.Mvc.HttpStatusCodeResult Microsoft.AspNetCore.Mvc.StatusCodeResult
Microsoft.AspNet.Mvc.HttpUnauthorizedResult Microsoft.AspNetCore.Mvc.UnauthorizedResult

ASP.NET 5 MVC compile views

To compile views, set the preserveCompilationContext option in project.json to preserve the compilation context, as shown here:

  "buildOptions": {
    "preserveCompilationContext": true

Changes in views

Views now support relative paths.

The Validation Summary Tag Helper asp-validation-summary attribute value has changed. Change:

<div asp-validation-summary="ValidationSummary.All"></div>


<div asp-validation-summary="All"></div>

Changes in ViewComponents

  • The sync APIs have been removed
  • Component.Render(), Component.RenderAsync(), and Component.Invoke() have been removed
  • To reduce ambiguity in View Component method selection, we’ve modified the selection to only allow exactly one Invoke() or InvokeAsync() per View Component
  • InvokeAsync() now takes an anonymous object instead of separate parameters
  • To use a view component, call @Component.InvokeAsync("Name of view component", <parameters>) from a view. The parameters will be passed to the InvokeAsync() method. The following example demonstrates the InvokeAsync() method call with two parameters:


@Component.InvokeAsync("Test", "MyName", 15)

ASP.NET Core 1.0:

@Component.InvokeAsync("Test", new { name = "MyName", age = 15 })
@Component.InvokeAsync("Test", new Dictionary<string, object> {
                       ["name"] = "MyName", ["age"] = 15 })
@Component.InvokeAsync<TestViewComponent>(new { name = "MyName", age = 15})

Updated controller discovery rules

There are changes that simplify controller discovery:

The new ControllerAttribute can be used to mark a class (and it’s subclasses) as a controller. A class whose name doesn’t end in Controller and derives from a base class that ends in Controller is no longer considered a controller. In this scenario, ControllerAttribute must be applied to the derived class itself or to the base class.

A type is considered a controller if all the following conditions are met:

  • The type is a public, concrete, non-open generic class
  • NonControllerAttribute is not applied to any type in its hierarchy
  • The type name ends with Controller, or ControllerAttribute is applied to the type or one of its ancestors.


If NonControllerAttribute is applied anywhere in the type hierarchy, the discovery conventions will never consider that type or its descendants to be a controller. In other words, NonControllerAttribute takes precedence over ControllerAttribute.


The IConfigurationSource interface has been introduced to represent the configuration used to build an IConfigurationProvider. It is no longer possible to access the provider instances from IConfigurationBuilder, only the sources. This is intentional, and may cause loss of functionality as you can no longer do things like call Load on the provider instances.

File-based configuration providers support both relative and absolute paths to configuration files. If you want to specify file paths relative to your application’s content root, you must call the SetBasePath extension method on IConfigurationBuilder:

public Startup(IHostingEnvironment env)
    var builder = new ConfigurationBuilder()

Automatic reload on change

The IConfigurationRoot.ReloadOnChanged extension method is no longer available. File-based configuration providers now provide extension methods to IConfigurationBuilder that allow you to specify whether configuration from those providers should be reloaded when there are changes in their files. See AddJsonFile, AddXmlFile and AddIniFile for details.


LogLevel.Verbose has been renamed to Trace and is now considered less severe than Debug.

The MinimumLevel property has been removed from ILoggerFactory. Each logging provider now provides extension methods to ILoggerFactory that allow specifying a minimum logging level. See AddConsole, AddDebug, and AddEventLog for details.


The signatures for the following methods or properties have changed:

ASP.NET 5 RC1 ASP.NET Core 1.0
ExternalLoginInfo.ExternalPrincipal ExternalLoginInfo.Principal
User.IsSignedIn() SignInManager.IsSignedIn(User)
UserManager.FindByIdAsync(HttpContext.User.GetUserId()) UserManager.GetUserAsync(HttpContext.User)
User.GetUserId() UserManager.GetUserId(User)

To use Identity in a view, add the following:

@using Microsoft.AspNetCore.Identity
@inject SignInManager<TUser> SignInManager
@inject UserManager<TUser> UserManager

Working with IIS

The package Microsoft.AspNetCore.IISPlatformHandler has been replaced by Microsoft.AspNetCore.Server.IISIntegration.

HttpPlatformHandler has been replaced by the ASP.NET Core Module (ANCM). The web.config file created by the Publish to IIS tool now configures IIS to the ANCM instead of HttpPlatformHandler to reverse-proxy requests.

The ASP.NET Core Module must be configured in web.config:

      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified"/>
    <aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%"
                stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout"

The Publish to IIS tool generates a correct web.config. See Publishing to IIS for more details.

IIS integration middleware is now configured when creating the Microsoft.AspNetCore.Hosting.WebHostBuilder, and is no longer called in the Configure method of the Startup class:

var host = new WebHostBuilder()

Web Deploy changes

Delete any <app name> - Web Deploy-publish.ps1 scripts created with Visual Studio web deploy using ASP.NET 5 RC1. The ASP.NET 5 RC1 scripts (which are DNX based) are not compatible with dotnet based scripts. Use Visual Studio to generate new web deploy scripts.

applicationhost.config changes

An applicationhost.config file created with ASP.NET 5 RC1 will point ASP.NET Core to an invalid content root location. With such a applicationhost.config file, ASP.NET Core will be configured with content root/web root as the content root folder and therefore look for web.config in Content root/wwwroot. The web.config file must be in the content root folder. When configured like this, the app will terminate with an HTTP 500 error.

Updating Launch Settings in Visual Studio

Update launchSettings.json to remove the web target and add the following:

  "WebApplication1": {
    "commandName": "Project",
    "launchBrowser": true,
    "launchUrl": "http://localhost:5000",
    "environmentVariables": {
      "ASPNETCORE_ENVIRONMENT": "Development"

Server garbage collection (GC)

You must turn on server garbage collection in project.json or app.config when running ASP.NET projects on the full .NET Framework:

   "runtimeOptions": {
     "configProperties": {
       "System.GC.Server": true