Nice! Consequently, the features of HubConnectionContext can be expanded in the future without making more constructors and breaking changes. The deprecated packages and npm modules were intended to integrate ASP.NET Core with various Single-Page App (SPA) frameworks. Consider the following example in Startup.ConfigureServices: Starting in ASP.NET Core 3.0, the ASP.NET Core shared framework (Microsoft.AspNetCore.App) only contains first-party assemblies that are fully developed, supported, and serviceable by Microsoft. This change was a result of adoption of the static web assets feature. Either add a reference to Microsoft.AspNetCore.Authorization.Policy or use AddAuthorizationCore instead. You can, however, download older versions of Chromium, which will suffice for testing. If your component requires ObjectPoolProvider, it needs to be added to your dependencies via the IServiceCollection. The extensibility was provided initially to allow pooling of the HttpContext, but it introduced unnecessary complexity and impeded other optimizations. I'll talk more about Interop and some of these related issues in Part 2 of this article. Implementations of IAuthorizationPolicyProvider didn't require a GetFallbackPolicyAsync method. endpoints.cors.max-age=1800 # How long, in seconds, the response from a pre-flight request can be cached by clients. @Cory - Unclear at this point. So yeah, it's all confusing as hell. For example: Version 13.0.19218.0 of the ASP.NET Core Module (ANCM) for hosting via IIS out-of-process enables an existing HTTPS redirection feature for ASP.NET Core 3.0 and 2.2 apps. For derived OAuth implementations, the most common change is to replace JObject.Parse with JsonDocument.Parse in the CreateTicketAsync override as shown here. In ASP.NET Core 3.0, the web stack was replatformed onto the generic host library. This is an example on how to configure CORS per site is in Apache: How often are they spotted? Perhaps the protocol, domain, hostname and port must be the same of your same domain when you want to access the desired frame. Two pages have the same origin if the protocol, port (if one is specified), and host are the same for both the webpages. Follow these instructions: Chrome; Firefox; This is The mitigations and solutions provided below account for the structural changes. In ASP.NET Core 3.0, most defaults were changed from SameSiteMode.Lax to SameSiteMode.None (but still using the prior standard). They won't, however, be included in the shared framework. It needs an Internet connection to work. The Microsoft.Extensions.Caching.SqlServer package will use the new Microsoft.Data.SqlClient package instead of System.Data.SqlClient package. We won't know until we see this in the wild though and it'll probably take a few update cycles before enough machines get these WebView2 runtime updates. HandshakeProtocol.SuccessHandshakeData was a public static ReadOnlyMemory field. For context, see dotnet/aspnetcore#3324. You can fairly easy create your own proxy, though it requires you to run node.js on your server. The code below is an example, where your proxy is located at /proxy on your server. The new behavior can be disabled by setting MvcOptions.SuppressAsyncSuffixInActionNames to false in Startup.ConfigureServices: By convention, asynchronous .NET methods are suffixed with Async. Edge alone does not provide it. You can switch to an