Restore default JUL root handler on Logback cleanup

core/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystem.java

@@ -76,6 +76,7 @@
  * @author Andy Wilkinson
  * @author Ben Hale
  * @author Dhruv Rastogi
+ * @author Rameel Rizvi
  * @since 1.0.0
  */
 public class LogbackLoggingSystem extends AbstractLoggingSystem implements BeanFactoryInitializationAotProcessor {
@@ -114,6 +115,8 @@ public FilterReply decide(Marker marker, ch.qos.logback.classic.Logger logger, L
 
 	private boolean bridgeHandlerInstalled;
 
+	private boolean rootConsoleHandlerRemoved;
+
 	public LogbackLoggingSystem(ClassLoader classLoader) {
 		super(classLoader);
 	}
@@ -182,6 +185,23 @@ private void removeDefaultRootHandler() {
 			Handler[] handlers = rootLogger.getHandlers();
 			if (handlers.length == 1 && handlers[0] instanceof ConsoleHandler) {
 				rootLogger.removeHandler(handlers[0]);
+				this.rootConsoleHandlerRemoved = true;
+			}
+		}
+		catch (Throwable ex) {
+			// Ignore and continue
+		}
+	}
+
+	private void restoreDefaultRootHandler() {
+		if (!this.rootConsoleHandlerRemoved) {
+			return;
+		}
+		this.rootConsoleHandlerRemoved = false;
+		try {
+			java.util.logging.Logger rootLogger = LogManager.getLogManager().getLogger("");
+			if (rootLogger.getHandlers().length == 0) {
+				rootLogger.addHandler(new ConsoleHandler());
 			}
 		}
 		catch (Throwable ex) {
@@ -340,6 +360,11 @@ public void cleanUp() {
 		super.cleanUp();
 		if (this.bridgeHandlerInstalled) {
 			removeJdkLoggingBridgeHandler();
+			// Restore the default JUL root handler that was removed when the bridge
+			// was installed. Without this, anything logged through JUL after cleanup
+			// (for example a startup failure reported via a JUL-backed commons-logging
+			// Log) would be silently discarded (see gh-50404).
+			restoreDefaultRootHandler();
 			this.bridgeHandlerInstalled = false;
 		}
 		context.getStatusManager().clear();

core/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

@@ -30,6 +30,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.logging.ConsoleHandler;
 import java.util.logging.Handler;
 import java.util.logging.LogManager;
 import java.util.stream.Stream;
@@ -108,6 +109,7 @@
  * @author Jonatan Ivanov
  * @author Moritz Halbritter
  * @author Dhruv Rastogi
+ * @author Rameel Rizvi
  */
 @ExtendWith(OutputCaptureExtension.class)
 @ClassPathExclusions({ "log4j-core-*.jar", "log4j-api-*.jar" })
@@ -355,6 +357,37 @@ void cleanUpLeavesBridgeHandlerInstalledByTheApplicationInPlace() {
 		}
 	}
 
+	@Test
+	void cleanUpRestoresDefaultRootHandlerToAvoidSilentlyDiscardingJulLogging(CapturedOutput output) {
+		// gh-50404: installing the bridge removes the default JUL root ConsoleHandler.
+		// If cleanUp does not restore it, anything subsequently logged through JUL
+		// (such as a startup failure reported via a JUL-backed commons-logging Log) is
+		// silently discarded. Start from the default single-ConsoleHandler state that a
+		// freshly started application has.
+		java.util.logging.Logger rootLogger = LogManager.getLogManager().getLogger("");
+		Handler[] originalHandlers = rootLogger.getHandlers();
+		for (Handler handler : originalHandlers) {
+			rootLogger.removeHandler(handler);
+		}
+		rootLogger.addHandler(new ConsoleHandler());
+		try {
+			this.loggingSystem.beforeInitialize();
+			assertThat(bridgeHandlerInstalled()).isTrue();
+			this.loggingSystem.cleanUp();
+			assertThat(rootLogger.getHandlers()).isNotEmpty();
+			java.util.logging.Logger.getLogger(getClass().getName()).severe("JUL logging after cleanup");
+			assertThat(output).contains("JUL logging after cleanup");
+		}
+		finally {
+			for (Handler handler : rootLogger.getHandlers()) {
+				rootLogger.removeHandler(handler);
+			}
+			for (Handler handler : originalHandlers) {
+				rootLogger.addHandler(handler);
+			}
+		}
+	}
+
 	@Test
 	void standardConfigLocations() {
 		String[] locations = this.loggingSystem.getStandardConfigLocations();