diff --git a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/JettyRequestUpgradeStrategy.java b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/JettyRequestUpgradeStrategy.java
index 41427095e75..3332d46d144 100644
--- a/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/JettyRequestUpgradeStrategy.java
+++ b/spring-web-reactive/src/main/java/org/springframework/web/reactive/socket/server/upgrade/JettyRequestUpgradeStrategy.java
@@ -37,11 +37,11 @@ import org.springframework.web.reactive.socket.adapter.JettyWebSocketHandlerAdap
 import org.springframework.web.reactive.socket.server.RequestUpgradeStrategy;
 import org.springframework.web.server.ServerWebExchange;
 
-
 /**
  * A {@link RequestUpgradeStrategy} for use with Jetty.
  * 
  * @author Violeta Georgieva
+ * @author Rossen Stoyanchev
  * @since 5.0
  */
 public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Lifecycle {
@@ -54,7 +54,7 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Life
 
 	private ServletContext servletContext;
 
-	private boolean running = false;
+	private volatile boolean running = false;
 
 	private final Object lifecycleMonitor = new Object();
 
@@ -69,7 +69,7 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Life
 					this.factory.setCreator((request, response) -> adapterHolder.get());
 					this.factory.start();
 				}
-				catch (Exception ex) {
+				catch (Throwable ex) {
 					throw new IllegalStateException("Unable to start WebSocketServerFactory", ex);
 				}
 			}
@@ -80,29 +80,25 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Life
 	public void stop() {
 		synchronized (this.lifecycleMonitor) {
 			if (isRunning()) {
+				this.running = false;
 				try {
 					this.factory.stop();
 				}
-				catch (Exception ex) {
+				catch (Throwable ex) {
 					throw new IllegalStateException("Failed to stop WebSocketServerFactory", ex);
 				}
-				finally {
-					this.running = false;
-				}
 			}
 		}
 	}
 
 	@Override
 	public boolean isRunning() {
-		synchronized (this.lifecycleMonitor) {
-			return this.running;
-		}
+		return this.running;
 	}
 
+
 	@Override
 	public Mono<Void> upgrade(ServerWebExchange exchange, WebSocketHandler handler) {
-
 		ServerHttpRequest request = exchange.getRequest();
 		ServerHttpResponse response = exchange.getResponse();
 		JettyWebSocketHandlerAdapter adapter = new JettyWebSocketHandlerAdapter(request, response, handler);
@@ -146,7 +142,7 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Life
 		synchronized (this.lifecycleMonitor) {
 			if (this.servletContext == null) {
 				this.servletContext = request.getServletContext();
-				this.servletContext.setAttribute(DecoratedObjectFactory.ATTR,  new DecoratedObjectFactory());
+				this.servletContext.setAttribute(DecoratedObjectFactory.ATTR, new DecoratedObjectFactory());
 				start();
 			}
 		}
diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java b/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
index bae6c82712b..0e9a7aefa98 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/server/jetty/JettyRequestUpgradeStrategy.java
@@ -65,9 +65,12 @@ import org.springframework.web.socket.server.RequestUpgradeStrategy;
  */
 public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, ServletContextAware, Lifecycle {
 
-	private static final ThreadLocal<WebSocketHandlerContainer> wsContainerHolder =
-			new NamedThreadLocal<>("WebSocket Handler Container");
+	private static final ThreadLocal<WebSocketHandlerContainer> containerHolder =
+			new NamedThreadLocal<>("WebSocketHandlerContainer");
 
+
+	// Configurable factory adapter due to Jetty 9.3.15+ API differences:
+	// using WebSocketServerFactory(ServletContext) as a version indicator
 	private final WebSocketServerFactoryAdapter factoryAdapter =
 			(ClassUtils.hasConstructor(WebSocketServerFactory.class, ServletContext.class) ?
 					new ModernJettyWebSocketServerFactoryAdapter() : new LegacyJettyWebSocketServerFactoryAdapter());
@@ -129,8 +132,8 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Serv
 	@Override
 	public void stop() {
 		if (isRunning()) {
+			this.running = false;
 			try {
-				this.running = false;
 				this.factoryAdapter.stop();
 			}
 			catch (Throwable ex) {
@@ -187,7 +190,7 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Serv
 				new WebSocketHandlerContainer(handlerAdapter, selectedProtocol, selectedExtensions);
 
 		try {
-			wsContainerHolder.set(container);
+			containerHolder.set(container);
 			this.factoryAdapter.getFactory().acceptWebSocket(servletRequest, servletResponse);
 		}
 		catch (IOException ex) {
@@ -195,7 +198,7 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Serv
 					"Response update failed during upgrade to WebSocket: " + request.getURI(), ex);
 		}
 		finally {
-			wsContainerHolder.remove();
+			containerHolder.remove();
 		}
 	}
 
@@ -263,7 +266,7 @@ public class JettyRequestUpgradeStrategy implements RequestUpgradeStrategy, Serv
 			this.factory.setCreator(new WebSocketCreator() {
 				@Override
 				public Object createWebSocket(ServletUpgradeRequest request, ServletUpgradeResponse response) {
-					WebSocketHandlerContainer container = wsContainerHolder.get();
+					WebSocketHandlerContainer container = containerHolder.get();
 					Assert.state(container != null, "Expected WebSocketHandlerContainer");
 					response.setAcceptedSubProtocol(container.getSelectedProtocol());
 					response.setExtensions(container.getExtensionConfigs());