ASP.NET Core and Blazor updates in .NET Core 3.0

Daniel Roth

ASP.NET Core and Blazor updates in .NET Core 3.0

Today we are thrilled to announce the release of .NET Core 3.0! .NET Core 3.0 is ready for production use, and is loaded with lots of great new features for building amazing web apps with ASP.NET Core and Blazor.

Some of the big new features in this release of ASP.NET Core include:

  • Build rich interactive client-side web apps using C# instead of JavaScript using Blazor).
  • Create high-performance backend services with gRPC.
  • SignalR now has support for automatic reconnection and client-to-server streaming.
  • Generate strongly typed client code for Web APIs with OpenAPI documents.
  • Endpoint routing integrated through the framework.
  • HTTP/2 now enabled by default in Kestrel.
  • Authentication support for Web APIs and single-page apps integrated with IdentityServer
  • Support for certificate and Kerberos authentication.
  • Integrates with the new System.Text.Json serializer.
  • New generic host sets up common hosting services like dependency injection (DI), configuration, and logging.
  • New Worker Service template for building long-running services.
  • New EventCounters created for requests per second, total requests, current requests, and failed requests.
  • Startup errors now reported to the Windows Event Log when hosted in IIS.
  • Request pipeline integrated with with System.IO.Pipelines.
  • Performance improvements across the entire stack.

You can find all the details about what’s new in ASP.NET Core in .NET Core 3.0 in the What’s new in ASP.NET Core 3.0 topic.

See the .NET Core 3.0 release notes for additional details and known issues.

Get started

To get started with ASP.NET Core in .NET Core 3.0 install the .NET Core 3.0 SDK.

If you’re on Windows using Visual Studio, install Visual Studio 2019 16.3, which includes .NET Core 3.0.

Note: .NET Core 3.0 requires Visual Studio 2019 16.3 or later.

There is also a Blazor WebAssembly preview update available with this release. This update to Blazor WebAssembly still has a Preview 9 version, but carries an updated build number. Blazor WebAssembly is still in preview and is not part of the .NET Core 3.0 release.

To install the latest Blazor WebAssembly template run the following command:

dotnet new -i Microsoft.AspNetCore.Blazor.Templates::3.0.0-preview9.19465.2

Upgrade an existing project

To upgrade an existing ASP.NET Core app to .NET Core 3.0, follow the migrations steps in the ASP.NET Core docs.

See the full list of breaking changes in ASP.NET Core 3.0.

To upgrade an existing ASP.NET Core 3.0 RC1 project to 3.0:

  • Update all Microsoft.AspNetCore.* and Microsoft.Extensions.* package references to 3.0.0
  • Update all Microsoft.AspNetCore.Blazor.* package references to 3.0.0-preview9.19465.2

That’s it! You should now be all set to use .NET Core 3.0!

Join us at .NET Conf!

Please join us at .NET Conf to learn all about the new features in .NET Core 3.0 and to celebrate the release with us! .NET Conf is a live streaming event open to everyone, and features talks from many talented speakers from the .NET team and the .NET community. Check out the schedule and attend a local event near you. Or join the Virtual Attendee Party for the chance to win prizes!

Give feedback

We hope you enjoy the new features in this release of ASP.NET Core and Blazor in .NET Core 3.0! We are eager to hear about your experiences with this latest .NET Core release. Let us know what you think by filing issues on GitHub.

Thanks for using ASP.NET Core and Blazor!


Discussion is closed. Login to edit/delete existing comments.

  • Steven Cramer 0

    Awesome! It has been a fun ride up to this point. May the fun continue. Thanks Dan!

  • Storc, Ondrej 0

    Nice! But are the package versions for Blazor correct?

    • Daniel RothMicrosoft employee 0

      Yes, I believe so. The Blazor WebAssembly packages are still in preview, so they have a preview9 based version number. If your hitting issues with packages versions let us know!

  • Madhu Sudhanan P 0

    Good work. Looking forward for production ready client side Blazor.

    • Chris Woodward 0

      +1 this
      We are also looking forward to production ready client-side Blazor.
      I believe the slides that Scott Hunter referred to in his .NET Conf Keynote showed a WebAssembly milestone scheduled for May 2020 so I guess we may see a client-side Blazor update around then.

      • Daniel RothMicrosoft employee 0

        Yes, we are now planning to ship Blazor WebAssembly in May of next year. Wohoo!

        • Nathan Berkowitz 0

          Will it have authentication and authorization?

  • Rod Macdonald 0

    Super news, another milestone!

    I checked the release notes, but if I have VS 19 16.0.1 and VS 19 16.3.2 Preview 2, what should I do regarding installing/uninstalling .NET Core SDKs and the latest VS?

    There are 3 aspects to this:
    I haven’t been able to reference the correct Blazor client side templates since Feb ’19 (.NET Preview 2?). Is there a way of properly removing SDK references? Some strange things going on there even after trying to remove from the command line;
    I’m pretty sure I should be able to see a message in my current (non preview) VS 19, telling me 16.3 is available. Alas nothing. Will I get a notification and I can just over-install?;
    what is the situation regarding VS Preview – can it be completely uninstalled or is it a test platform moving forwards pending the release of Blazor client side?

    Thank you!

    • Adan Jauregui 0

      Check the Visual Studio Installer bundled with VS. It should guide you to upgrade to the stable 16.3 release.

      If you don’t need the preview anymore, you can remove it with confidence.

      • Rod Macdonald 0

        Thanks for the feedback. The 16.3 upgrade went smoothly. Do you know which client side Blazor template version I should have (currently there are 2 instances of them, both 010184 with the same description)? Is there a tool to remove old SDKs – command line and apps uninstall don’t work?

        My question about the preview was, do I need it for future Blazor releases moving forwards?

        • Adan Jauregui 0

          Well, actually is kinda confusing. Client-side Blazor is still in preview and it has been released a separated template.

          Honestly, that’s the question only Dan Roth knows about 😀

          • Rod Macdonald 0

            Just found out 010184 is February’s preview 2 SDK. Tried the same in preview 16.4 with the same problem. VS 16.3 shows no Blazor template version at all. Both show 2 instances of Blazor WebAssembly templates – this is driving me nuts!

            If it helps anyone, assuming the correct Blazor WebAssembly template is now installed (now reporting CLI v3.0.100 with no mention of preview9.19465.2), I was getting old and multiple versions. So, I removed all the old SDKs I could via Setting, Apps, Uninstall – then manually deleted a load of SDK preview folders under C:\Prgram Files\dotnet. Previews 2, 7 and 8 seemed to block the install of preview 9 and to cause the issue reported.

            If I have the correct template, then would suggest PMC and the template dialogue report the preview number as before. If I don’t have the correct template still then bubble!

            Finally is there a way I can definitely see that I have indeed the correct version?

  • Ben Hayat 0

    Authentication support for Web APIs and single-page apps integrated with IdentityServer

    Hi Dan;
    Is this support only for the two templates (Angular and React) that is provided or will this work with any JS client like Vue?
    The Docs solely focus on React and Angular.


    • Daniel RothMicrosoft employee 0

      Yes, the authentication support should work with Vue as well. Let us know how it works for you!

  • Tobias Punke 0

    Great stuff. Blazor is AWESOME!!!

  • Sergiy Korzh 0

    IdentityServer – is it the same as the well-known IdentityServer4 library?

    • Daniel RothMicrosoft employee 0


  • Robert swilley 0

    Awesome work to everyone involved! When does Blazor Server Side going to go GA? I thought it was going to be in the .NET Core 3.0 release?

    • Daniel RothMicrosoft employee 0

      Blazor Server is part of .NET Core 3.0 and is now supported for production use.

      Blazor WebAssembly is still in preview, but we announced at .NET Conf this week that we expect to ship it in May 2020.

      • Robert swilley 0

        Nice! I had read another blog post about all the great .net core 3.0 updates that didn’t mention Blazor at all. That confused me a bit. I’m super excited to play around with Blazor Server, and I can’t wait for client-side!

  • Stilgar Naib 0

    Anything we need to know about ASP.NET Core Identity 3.0? Any breaking changes?

  • Mohamed Aladdin 0

    Will there be NuGet packages for ASP.NET Core 3.0 any time soon?

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