[main] Revert Enforce WebSockets Transport for Blazor

src/Components/Server/src/Builder/ComponentEndpointRouteBuilderExtensions.cs

@@ -52,8 +52,7 @@ public static ComponentEndpointConventionBuilder MapBlazorHub(
                 throw new ArgumentNullException(nameof(path));
             }
 
-            // Only support the WebSockets transport type by default
-            return endpoints.MapBlazorHub(path, configureOptions: options => { options.Transports = HttpTransportType.WebSockets; });
+            return endpoints.MapBlazorHub(path, configureOptions: _ => { });
         }
 
         /// <summary>

src/Components/Web.JS/src/Boot.Server.ts

@@ -1,6 +1,6 @@
 import { DotNet } from '@microsoft/dotnet-js-interop';
 import { Blazor } from './GlobalExports';
-import { HubConnectionBuilder, HubConnection, HttpTransportType } from '@microsoft/signalr';
+import { HubConnectionBuilder, HubConnection } from '@microsoft/signalr';
 import { MessagePackHubProtocol } from '@microsoft/signalr-protocol-msgpack';
 import { showErrorNotification } from './BootErrors';
 import { shouldAutoStart } from './BootCommon';
@@ -86,7 +86,7 @@ async function initializeConnection(options: CircuitStartOptions, logger: Logger
   (hubProtocol as unknown as { name: string }).name = 'blazorpack';
 
   const connectionBuilder = new HubConnectionBuilder()
-    .withUrl('_blazor', HttpTransportType.WebSockets)
+    .withUrl('_blazor')
     .withHubProtocol(hubProtocol);
 
   options.configureSignalR(connectionBuilder);
@@ -144,14 +144,7 @@ async function initializeConnection(options: CircuitStartOptions, logger: Logger
       // Throw this exception so it can be handled at the reconnection layer, and don't show the
       // error notification.
       throw ex;
-    } else if (!isNestedError(ex)) {
-      showErrorNotification();
-    } else if (ex.innerErrors && ex.innerErrors.some(e => e.errorType === 'UnsupportedTransportError' && e.transport === HttpTransportType.WebSockets)) {
-      showErrorNotification('Unable to connect, please ensure you are using an updated browser that supports WebSockets.');
-    } else if (ex.innerErrors && ex.innerErrors.some(e => e.errorType === 'FailedToStartTransportError' && e.transport === HttpTransportType.WebSockets)) {
-      showErrorNotification('Unable to connect, please ensure WebSockets are available. A VPN or proxy may be blocking the connection.');
-    } else if (ex.innerErrors && ex.innerErrors.some(e => e.errorType === 'DisabledTransportError' && e.transport === HttpTransportType.LongPolling)) {
-      logger.log(LogLevel.Error, 'Unable to initiate a SignalR connection to the server. This might be because the server is not configured to support WebSockets. To troubleshoot this, visit https://aka.ms/blazor-server-websockets-error.');
+    } else {
       showErrorNotification();
     }
   }
@@ -169,14 +162,8 @@ async function initializeConnection(options: CircuitStartOptions, logger: Logger
   });
 
   return connection;
-
-  function isNestedError(error: any): error is AggregateError {
-    return error && ('innerErrors' in error);
-  }
 }
 
-type AggregateError = Error & { innerErrors: { errorType: string, transport: HttpTransportType }[] };
-
 function unhandledError(connection: HubConnection, err: Error, logger: Logger): void {
   logger.log(LogLevel.Error, err);
 

src/Components/Web.JS/src/BootErrors.ts

@@ -1,13 +1,9 @@
 let hasFailed = false;
 
-export async function showErrorNotification(customErrorMessage: string = '') {
+export async function showErrorNotification() {
     let errorUi = document.querySelector('#blazor-error-ui') as HTMLElement;
     if (errorUi) {
         errorUi.style.display = 'block';
-
-        if (customErrorMessage && errorUi.firstChild) {
-            errorUi.firstChild.textContent = `\n\t${customErrorMessage}\t\n`;
-        }
     }
 
     if (!hasFailed) {

src/Components/test/testassets/TestServer/ServerStartup.cs

@@ -42,7 +42,7 @@ public void ConfigureServices(IServiceCollection services)
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
-        public virtual void Configure(IApplicationBuilder app, IWebHostEnvironment env, ResourceRequestLog resourceRequestLog)
+        public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ResourceRequestLog resourceRequestLog)
         {
             var enUs = new CultureInfo("en-US");
             CultureInfo.DefaultThreadCurrentCulture = enUs;