diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowReactiveWebServerFactory.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowReactiveWebServerFactory.java
index 08a33832f7..ab26aa5b76 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowReactiveWebServerFactory.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowReactiveWebServerFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -117,6 +117,7 @@ public class UndertowReactiveWebServerFactory extends AbstractReactiveWebServerF
 		else {
 			builder.addHttpListener(port, getListenAddress());
 		}
+		builder.setServerOption(UndertowOptions.SHUTDOWN_TIMEOUT, 0);
 		for (UndertowBuilderCustomizer customizer : this.builderCustomizers) {
 			customizer.customize(builder);
 		}
diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactory.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactory.java
index 8dc3b442e4..89b5bc2c8a 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactory.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -241,6 +241,7 @@ public class UndertowServletWebServerFactory extends AbstractServletWebServerFac
 		else {
 			builder.addHttpListener(port, getListenAddress());
 		}
+		builder.setServerOption(UndertowOptions.SHUTDOWN_TIMEOUT, 0);
 		for (UndertowBuilderCustomizer customizer : this.builderCustomizers) {
 			customizer.customize(builder);
 		}
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java
index 8dfbe18a5e..e2cc94f6af 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java
@@ -23,7 +23,10 @@ import java.nio.charset.StandardCharsets;
 import java.security.KeyStore;
 import java.time.Duration;
 import java.util.Arrays;
+import java.util.concurrent.BrokenBarrierException;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.CyclicBarrier;
 
 import javax.net.ssl.KeyManagerFactory;
 import javax.net.ssl.SSLException;
@@ -333,6 +336,31 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 				.hasMessageContaining("Could not load key store 'null'");
 	}
 
+	@Test
+	void whenARequestIsActiveThenStopWillComplete() throws InterruptedException, BrokenBarrierException {
+		AbstractReactiveWebServerFactory factory = getFactory();
+		CyclicBarrier barrier = new CyclicBarrier(2);
+		CountDownLatch latch = new CountDownLatch(1);
+		this.webServer = factory.getWebServer((request, response) -> {
+			try {
+				barrier.await();
+				latch.await();
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+			}
+			catch (BrokenBarrierException ex) {
+				throw new IllegalStateException(ex);
+			}
+			return response.setComplete();
+		});
+		this.webServer.start();
+		new Thread(() -> getWebClient().build().get().uri("/").exchange().block()).start();
+		barrier.await();
+		this.webServer.stop();
+		latch.countDown();
+	}
+
 	protected WebClient prepareCompressionTest() {
 		Compression compression = new Compression();
 		compression.setEnabled(true);
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/server/AbstractServletWebServerFactoryTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/server/AbstractServletWebServerFactoryTests.java
index c7098f14eb..56acfe94cc 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/server/AbstractServletWebServerFactoryTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/server/AbstractServletWebServerFactoryTests.java
@@ -45,7 +45,10 @@ import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
+import java.util.concurrent.BrokenBarrierException;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.CyclicBarrier;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.zip.GZIPInputStream;
@@ -986,6 +989,43 @@ public abstract class AbstractServletWebServerFactoryTests {
 				.satisfies(this::wrapsFailingServletException);
 	}
 
+	@Test
+	void whenARequestIsActiveThenStopWillComplete() throws InterruptedException, BrokenBarrierException {
+		AbstractServletWebServerFactory factory = getFactory();
+		CyclicBarrier barrier = new CyclicBarrier(2);
+		CountDownLatch latch = new CountDownLatch(1);
+		this.webServer = factory.getWebServer((context) -> context.addServlet("blocking", new HttpServlet() {
+
+			@Override
+			protected void doGet(HttpServletRequest req, HttpServletResponse resp)
+					throws ServletException, IOException {
+				try {
+					barrier.await();
+					latch.await();
+				}
+				catch (InterruptedException ex) {
+					Thread.currentThread().interrupt();
+				}
+				catch (BrokenBarrierException ex) {
+					throw new ServletException(ex);
+				}
+			}
+
+		}).addMapping("/"));
+		this.webServer.start();
+		new Thread(() -> {
+			try {
+				getResponse(getLocalUrl("/"));
+			}
+			catch (Exception ex) {
+				// Continue
+			}
+		}).start();
+		barrier.await();
+		this.webServer.stop();
+		latch.countDown();
+	}
+
 	private void wrapsFailingServletException(WebServerException ex) {
 		Throwable cause = ex.getCause();
 		while (cause != null) {