Fixes

Author: javiercn

src/Components/Endpoints/src/RazorComponentEndpointInvoker.cs

@@ -35,8 +35,12 @@ public Task Render(HttpContext context)
     private async Task RenderComponentCore(HttpContext context)
     {
         context.Response.ContentType = RazorComponentResultExecutor.DefaultContentType;
-        _renderer.InitializeStreamingRenderingFraming(context);
-        EndpointHtmlRenderer.MarkAsAllowingEnhancedNavigation(context);
+        var isErrorHandler = context.Features.Get<IExceptionHandlerFeature>() is not null;
+        _renderer.InitializeStreamingRenderingFraming(context, isErrorHandler);
+        if (!isErrorHandler)
+        {
+            EndpointHtmlRenderer.MarkAsAllowingEnhancedNavigation(context);
+        }
 
         var endpoint = context.GetEndpoint() ?? throw new InvalidOperationException($"An endpoint must be set on the '{nameof(HttpContext)}'.");
 
@@ -84,7 +88,7 @@ await EndpointHtmlRenderer.InitializeStandardComponentServicesAsync(
             context,
             rootComponent,
             ParameterView.Empty,
-            waitForQuiescence: result.IsPost);
+            waitForQuiescence: result.IsPost || isErrorHandler);
 
         Task quiesceTask;
         if (!result.IsPost)
@@ -123,8 +127,11 @@ await EndpointHtmlRenderer.InitializeStandardComponentServicesAsync(
         }
 
         // Emit comment containing state.
-        var componentStateHtmlContent = await _renderer.PrerenderPersistedStateAsync(context);
-        componentStateHtmlContent.WriteTo(bufferWriter, HtmlEncoder.Default);
+        if (!isErrorHandler)
+        {
+            var componentStateHtmlContent = await _renderer.PrerenderPersistedStateAsync(context);
+            componentStateHtmlContent.WriteTo(bufferWriter, HtmlEncoder.Default);
+        }
 
         // Invoke FlushAsync to ensure any buffered content is asynchronously written to the underlying
         // response asynchronously. In the absence of this line, the buffer gets synchronously written to the

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Streaming.cs

@@ -19,10 +19,11 @@ internal partial class EndpointHtmlRenderer
     private TextWriter? _streamingUpdatesWriter;
     private HashSet<int>? _visitedComponentIdsInCurrentStreamingBatch;
     private string? _ssrFramingCommentMarkup;
-    private bool _allowBoundaryMarkers;
+    private bool _isHandlingErrors;
 
-    public void InitializeStreamingRenderingFraming(HttpContext httpContext)
+    public void InitializeStreamingRenderingFraming(HttpContext httpContext, bool isErrorHandler)
     {
+        _isHandlingErrors = isErrorHandler;
         if (IsProgressivelyEnhancedNavigation(httpContext.Request))
         {
             var id = Guid.NewGuid().ToString();
@@ -202,19 +203,19 @@ protected override void RenderChildComponent(TextWriter output, ref RenderTreeFr
     {
         var componentId = componentFrame.ComponentId;
         var sequenceAndKey = new SequenceAndKey(componentFrame.Sequence, componentFrame.ComponentKey);
-        WriteComponentHtml(componentId, output, _allowBoundaryMarkers, sequenceAndKey);
+        WriteComponentHtml(componentId, output, allowBoundaryMarkers: true, sequenceAndKey);
     }
 
     private void WriteComponentHtml(int componentId, TextWriter output, bool allowBoundaryMarkers, SequenceAndKey sequenceAndKey = default)
     {
         _visitedComponentIdsInCurrentStreamingBatch?.Add(componentId);
 
         var componentState = (EndpointComponentState)GetComponentState(componentId);
-        var renderBoundaryMarkers = allowBoundaryMarkers && componentState.StreamRendering;
+        var renderBoundaryMarkers = allowBoundaryMarkers && componentState.StreamRendering && !_isHandlingErrors;
 
         ComponentEndMarker? endMarkerOrNull = default;
 
-        if (componentState.Component is SSRRenderModeBoundary boundary)
+        if (componentState.Component is SSRRenderModeBoundary boundary && !_isHandlingErrors)
         {
             var marker = boundary.ToMarker(_httpContext, sequenceAndKey.Sequence, sequenceAndKey.Key);
             endMarkerOrNull = marker.ToEndMarker();
@@ -246,7 +247,7 @@ private void WriteComponentHtml(int componentId, TextWriter output, bool allowBo
             output.Write("-->");
         }
 
-        if (endMarkerOrNull is { } endMarker)
+        if (endMarkerOrNull is { } endMarker && !_isHandlingErrors)
         {
             var serializedEndRecord = JsonSerializer.Serialize(endMarker, ServerComponentSerializationSettings.JsonSerializationOptions);
             output.Write("<!--Blazor:");

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.cs

@@ -12,7 +12,6 @@
 using Microsoft.AspNetCore.Components.Rendering;
 using Microsoft.AspNetCore.Components.RenderTree;
 using Microsoft.AspNetCore.Components.Routing;
-using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Routing;
@@ -60,7 +59,6 @@ private void SetHttpContext(HttpContext httpContext)
         if (_httpContext is null)
         {
             _httpContext = httpContext;
-            _allowBoundaryMarkers = _httpContext.Features.Get<IExceptionHandlerFeature>() is null;
         }
         else if (_httpContext != httpContext)
         {

src/Components/Endpoints/src/Results/RazorComponentResultExecutor.cs

@@ -5,6 +5,7 @@
 using System.Buffers;
 using System.Text;
 using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.DependencyInjection;
@@ -46,7 +47,8 @@ private static Task RenderComponentToResponse(
         var endpointHtmlRenderer = httpContext.RequestServices.GetRequiredService<EndpointHtmlRenderer>();
         return endpointHtmlRenderer.Dispatcher.InvokeAsync(async () =>
         {
-            endpointHtmlRenderer.InitializeStreamingRenderingFraming(httpContext);
+            var isErrorHandler = httpContext.Features.Get<IExceptionHandlerFeature>() is not null;
+            endpointHtmlRenderer.InitializeStreamingRenderingFraming(httpContext, isErrorHandler);
             EndpointHtmlRenderer.MarkAsAllowingEnhancedNavigation(httpContext);
 
             // We could pool these dictionary instances if we wanted, and possibly even the ParameterView

src/Components/test/E2ETest/ServerRenderingTests/ErrorHandlingTest.cs

@@ -31,6 +31,7 @@ public void RendersExceptionFromComponent()
             Browser.FindElements(By.CssSelector(".text-danger")),
             item => Assert.Equal("Error.", item.Text),
             item => Assert.Equal("An error occurred while processing your request.", item.Text));
+        Browser.Equal("False", () => Browser.FindElement(By.Id("is-interactive-server")).Text);
     }
 
     private void GoTo(string relativePath)

src/Components/test/testassets/Components.TestServer/Components.TestServer.csproj

@@ -43,4 +43,10 @@
     </AssemblyAttribute>
   </ItemGroup>
 
+  <ItemGroup>
+    <Content Update="RazorComponents\Pages\ErrorLayout.razor">
+      <ExcludeFromSingleFile>true</ExcludeFromSingleFile>
+    </Content>
+  </ItemGroup>
+
 </Project>

src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/Error.razor

@@ -1,4 +1,5 @@
 @page "/Error"
+@layout ErrorLayout
 @using System.Diagnostics
 
 <PageTitle>Error</PageTitle>

src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/ErrorLayout.razor

@@ -0,0 +1,7 @@
+@inherits Microsoft.AspNetCore.Components.LayoutComponentBase
+
+<ServerInteractiveCounter />
+
+<div>
+    @Body
+</div>