C# – How to migrate .NET Core 2.2 Web API to .NET Core 3.0

.net coreasp.net-coreasp.net-core-3.0asp.net-core-mvcc

I was following Microsoft's migration guide, but failed. So, instead, I created a new project with .NET 2.2 to establish a clean template, and then tried migrating to .NET Core 3.0. But it once again failed. In the Startup.cs, the dependency injection cannot find the method services.AddMvc().

It seems my code still refers to .NET 2.2 instead of .NET 3.0.

If I run dotnet watch run, I get the following error:

Application startup exception System.InvalidOperationException:
Endpoint Routing does not support 'IApplicationBuilder.UseMvc(…)'.
To use 'IApplicationBuilder.UseMvc' set
'MvcOptions.EnableEndpointRouting = false' inside
'ConfigureServices(…). at
Microsoft.AspNetCore.Builder.MvcApplicationBuilderExtensions.UseMvc(IApplicationBuilder
app, Action'1 configureRoutes) at
Microsoft.AspNetCore.Builder.MvcApplicationBuilderExtensions.UseMvc(IApplicationBuilder
app) at netmig.Startup.Configure(IApplicationBuilder app,
IHostingEnvironment env) in E:\testapp\netmig\Startup.cs:line 46 at
System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags
invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Microsoft.AspNetCore.Hosting.ConfigureBuilder.Invoke(Object
instance, IApplicationBuilder builder) at
Microsoft.AspNetCore.Hosting.ConfigureBuilder.<>c__DisplayClass4_0.b__0(IApplicationBuilder
builder) at
Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass13_0.b__2(IApplicationBuilder
app) at
Microsoft.AspNetCore.Mvc.Filters.MiddlewareFilterBuilderStartupFilter.<>c__DisplayClass0_0.g__MiddlewareFilterBuilder|0(IApplicationBuilder
builder) at
Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.b__0(IApplicationBuilder
app) at
Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken
cancellationToken) Unhandled exception.
System.InvalidOperationException: Endpoint Routing does not support
'IApplicationBuilder.UseMvc(…)'. To use 'IApplicationBuilder.UseMvc'
set 'MvcOptions.EnableEndpointRouting = false' inside
'ConfigureServices(…). at
Microsoft.AspNetCore.Builder.MvcApplicationBuilderExtensions.UseMvc(IApplicationBuilder
app, Action'1 configureRoutes) at
Microsoft.AspNetCore.Builder.MvcApplicationBuilderExtensions.UseMvc(IApplicationBuilder
app) at netmig.Startup.Configure(IApplicationBuilder app,
IHostingEnvironment env) in E:\testapp\netmig\Startup.cs:line 46 at
System.RuntimeMethodHandle.InvokeMethod(Object target, Object[]
arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags
invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Microsoft.AspNetCore.Hosting.ConfigureBuilder.Invoke(Object
instance, IApplicationBuilder builder) at
Microsoft.AspNetCore.Hosting.ConfigureBuilder.<>c__DisplayClass4_0.b__0(IApplicationBuilder
builder) at
Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass13_0.b__2(IApplicationBuilder
app) at
Microsoft.AspNetCore.Mvc.Filters.MiddlewareFilterBuilderStartupFilter.<>c__DisplayClass0_0.g__MiddlewareFilterBuilder|0(IApplicationBuilder
builder) at
Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.b__0(IApplicationBuilder
app) at
Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken
cancellationToken) at
Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken
cancellationToken) at
Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost
host, CancellationToken token) at
Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost
host, CancellationToken token) at
Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost
host) at netmig.Program.Main(String[] args) in
E:\testapp\netmig\Program.cs:line 18 watch : Exited with error code
-532462766

The full code I am running can be found on GitHub. My .NET info:

dotnet –info .NET Core SDK (reflecting any global.json): Version:
3.0.100 Commit: 04339c3a26

Runtime Environment: OS Name: Windows OS Version:
10.0.18362 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\3.0.100\

Host (useful for support): Version: 3.0.0 Commit: 7d57652f33

.NET Core SDKs installed:
2.2.401 [C:\Program Files\dotnet\sdk]
3.0.100 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.2.6
[C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.6 [C:\Program
Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.0 [C:\Program
Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App
2.2.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.0.0 [C:\Program
Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.0.0 [C:\Program
Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

Best Answer

For v2.2

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseMvc();
    }

And for v3

public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }

Also make sure your csproj is target .net core 3.0

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

Related Solutions

.net – the difference between .NET Core and .NET Standard Class Library project types

When should we use one over the other?

The decision is a trade-off between compatibility and API access.

Use a .NET Standard library when you want to increase the number of applications that will be compatible with your library, and you are okay with a decrease in the .NET API surface area your library can access.

Use a .NET Core library when you want to increase the .NET API surface area your library can access, and you are okay with allowing only .NET Core applications to be compatible with your library.

For example, a library that targets .NET Standard 1.3 will be compatible with applications that target .NET Framework 4.6, .NET Core 1.0, Universal Windows Platform 10.0, and any other platform that supports .NET Standard 1.3. The library will not have access to some parts of the .NET API, though. For instance, the Microsoft.NETCore.CoreCLR package is compatible with .NET Core, but not with .NET Standard.

What is the difference between Class Library (.NET Standard) and Class Library (.NET Core)?

Compatibility: Libraries that target .NET Standard will run on any .NET Standard compliant runtime, such as .NET Core, .NET Framework, Mono/Xamarin. On the other hand, libraries that target .NET Core can only run on the .NET Core runtime.

API Surface Area: .NET Standard libraries come with everything in NETStandard.Library, whereas .NET Core libraries come with everything in Microsoft.NETCore.App. The latter includes approximately 20 additional libraries, some of which we can add manually to our .NET Standard library (such as System.Threading.Thread) and some of which are not compatible with the .NET Standard (such as Microsoft.NETCore.CoreCLR).

Also, .NET Core libraries specify a runtime and come with an application model. That's important, for instance, to make unit test class libraries runnable.

Why do both exist?

Ignoring libraries for a moment, the reason that .NET Standard exists is for portability; it defines a set of APIs that .NET platforms agree to implement. Any platform that implements a .NET Standard is compatible with libraries that target that .NET Standard. One of those compatible platforms is .NET Core.

Coming back to libraries, the .NET Standard library templates exist to run on multiple runtimes (at the expense of API surface area). Conversely, the .NET Core library templates exist to access more API surface area (at the expense of compatibility) and to specify a platform against which to build an executable.

Here is an interactive matrix that shows which .NET Standard supports which .NET implementation(s) and how much API surface area is available.

Docker – Error: It was not possible to find any installed .NET Core SDKs

For me it happened when I had wrong ENTRYPOINT in my DOCKERFILE

# Build runtime image
FROM mcr.microsoft.com/dotnet/core/aspnet:3.1
WORKDIR /app
COPY --from=build-env /app/out .
ENTRYPOINT ["dotnet", "SampleAppForDocker.dll"]

Make sure that you run correct dll in your ENTRYPOINT. I had wrong name of dll file.

Best Answer

Related Solutions

.net – the difference between .NET Core and .NET Standard Class Library project types

Docker – Error: It was not possible to find any installed .NET Core SDKs

Related Topic