WebAsyncManager wraps disconnected client errors

If the Servlet container delegates a disconnected client error via
AsyncListener#onError, wrap it as AsyncRequestNotUsableException
for more targeted and consistent handling of such errors.

Closes gh-34363

spring-web/src/main/java/org/springframework/web/context/request/async/WebAsyncManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,6 +34,7 @@ import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.context.request.RequestAttributes;
 import org.springframework.web.context.request.async.DeferredResult.DeferredResultHandler;
+import org.springframework.web.util.DisconnectedClientHelper;
 
 /**
  * The central class for managing asynchronous request processing, mainly intended
@@ -350,6 +351,10 @@ public final class WebAsyncManager {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Servlet container error notification for " + formatUri(this.asyncWebRequest) + ": " + ex);
 			}
+			if (DisconnectedClientHelper.isClientDisconnectedException(ex)) {
+				ex = new AsyncRequestNotUsableException(
+						"Servlet container error notification for disconnected client", ex);
+			}
 			Object result = interceptorChain.triggerAfterError(this.asyncWebRequest, callable, ex);
 			result = (result != CallableProcessingInterceptor.RESULT_NONE ? result : ex);
 			setConcurrentResultAndDispatch(result);
@@ -442,6 +447,10 @@ public final class WebAsyncManager {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Servlet container error notification for " + formatUri(this.asyncWebRequest));
 			}
+			if (DisconnectedClientHelper.isClientDisconnectedException(ex)) {
+				ex = new AsyncRequestNotUsableException(
+						"Servlet container error notification for disconnected client", ex);
+			}
 			try {
 				interceptorChain.triggerAfterError(this.asyncWebRequest, deferredResult, ex);
 				synchronized (WebAsyncManager.this) {

spring-web/src/test/java/org/springframework/web/context/request/async/WebAsyncManagerErrorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 package org.springframework.web.context.request.async;
 
+import java.io.IOException;
 import java.util.concurrent.Callable;
 
 import jakarta.servlet.AsyncEvent;
@@ -152,6 +153,22 @@ class WebAsyncManagerErrorTests {
 		verify(interceptor).beforeConcurrentHandling(this.asyncWebRequest, callable);
 	}
 
+	@Test // gh-34363
+	void startCallableProcessingDisconnectedClient() throws Exception {
+		StubCallable callable = new StubCallable();
+		this.asyncManager.startCallableProcessing(callable);
+
+		IOException ex = new IOException("broken pipe");
+		AsyncEvent event = new AsyncEvent(new MockAsyncContext(this.servletRequest, this.servletResponse), ex);
+		this.asyncWebRequest.onError(event);
+
+		MockAsyncContext asyncContext = (MockAsyncContext) this.servletRequest.getAsyncContext();
+		assertThat(this.asyncManager.hasConcurrentResult()).isTrue();
+		assertThat(this.asyncManager.getConcurrentResult())
+				.as("Disconnected client error not wrapped AsyncRequestNotUsableException")
+				.isOfAnyClassIn(AsyncRequestNotUsableException.class);
+	}
+
 	@Test
 	void startDeferredResultProcessingErrorAndComplete() throws Exception {
 
@@ -259,6 +276,21 @@ class WebAsyncManagerErrorTests {
 		assertThat(((MockAsyncContext) this.servletRequest.getAsyncContext()).getDispatchedPath()).isEqualTo("/test");
 	}
 
+	@Test // gh-34363
+	void startDeferredResultProcessingDisconnectedClient() throws Exception {
+		DeferredResult<Object> deferredResult = new DeferredResult<>();
+		this.asyncManager.startDeferredResultProcessing(deferredResult);
+
+		IOException ex = new IOException("broken pipe");
+		AsyncEvent event = new AsyncEvent(new MockAsyncContext(this.servletRequest, this.servletResponse), ex);
+		this.asyncWebRequest.onError(event);
+
+		assertThat(this.asyncManager.hasConcurrentResult()).isTrue();
+		assertThat(deferredResult.getResult())
+				.as("Disconnected client error not wrapped AsyncRequestNotUsableException")
+				.isOfAnyClassIn(AsyncRequestNotUsableException.class);
+	}
+
 
 	private static final class StubCallable implements Callable<Object> {
 		@Override