diff --git a/logback-classic/src/main/java/ch/qos/logback/classic/LoggerContext.java b/logback-classic/src/main/java/ch/qos/logback/classic/LoggerContext.java
index 8177756892..8faed3ed3c 100755
--- a/logback-classic/src/main/java/ch/qos/logback/classic/LoggerContext.java
+++ b/logback-classic/src/main/java/ch/qos/logback/classic/LoggerContext.java
@@ -1,13 +1,13 @@
 /**
  * Logback: the reliable, generic, fast and flexible logging framework.
  * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
- *
+ * <p>
  * This program and the accompanying materials are dual-licensed under
  * either the terms of the Eclipse Public License v1.0 as published by
  * the Eclipse Foundation
- *
- *   or (per the licensee's choosing)
- *
+ * <p>
+ * or (per the licensee's choosing)
+ * <p>
  * under the terms of the GNU Lesser General Public License version 2.1
  * as published by the Free Software Foundation.
  */
@@ -23,6 +23,7 @@
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.locks.ReentrantLock;
 
 import ch.qos.logback.classic.util.LogbackMDCAdapter;
 import ch.qos.logback.core.status.ErrorStatus;
@@ -57,7 +58,9 @@
  */
 public class LoggerContext extends ContextBase implements ILoggerFactory, LifeCycle {
 
-    /** Default setting of packaging data in stack traces */
+    /**
+     * Default setting of packaging data in stack traces
+     */
     public static final boolean DEFAULT_PACKAGING_DATA = false;
 
     final Logger root;
@@ -74,7 +77,6 @@ public class LoggerContext extends ContextBase implements ILoggerFactory, LifeCy
 
     MDCAdapter mdcAdapter;
 
-
     private int maxCallerDataDepth = ClassicConstants.DEFAULT_MAX_CALLEDER_DATA_DEPTH;
 
     int resetCount = 0;
@@ -91,6 +93,10 @@ public LoggerContext() {
         initEvaluatorMap();
         size = 1;
         this.frameworkPackages = new ArrayList<String>();
+        // In 1.5.7, the stop() method assumes that at some point the context has been started
+        // since earlier versions of logback did not mandate calling the start method
+        // we need to call in the constructor
+        this.start();
     }
 
     void initEvaluatorMap() {
@@ -117,8 +123,6 @@ public void setName(String name) {
         updateLoggerContextVO();
     }
 
-
-
     public final Logger getLogger(final Class<?> clazz) {
         return getLogger(clazz.getName());
     }
@@ -194,9 +198,7 @@ public Logger exists(String name) {
 
     final void noAppenderDefinedWarning(final Logger logger) {
         if (noAppenderWarning++ == 0) {
-            getStatusManager().add(new WarnStatus(
-                    "No appenders present in context [" + getName() + "] for logger [" + logger.getName() + "].",
-                    logger));
+            getStatusManager().add(new WarnStatus("No appenders present in context [" + getName() + "] for logger [" + logger.getName() + "].", logger));
         }
     }
 
@@ -219,17 +221,24 @@ public boolean isPackagingDataEnabled() {
         return packagingDataEnabled;
     }
 
-    private void cancelScheduledTasks() {
-        for (ScheduledFuture<?> sf : scheduledFutures) {
-            sf.cancel(false);
+    void cancelScheduledTasks() {
+
+        try {
+            configurationLock.lock();
+
+            for (ScheduledFuture<?> sf : scheduledFutures) {
+                sf.cancel(false);
+            }
+            scheduledFutures.clear();
+        } finally {
+            configurationLock.unlock();
         }
-        scheduledFutures.clear();
     }
 
     private void resetStatusListenersExceptResetResistant() {
         StatusManager sm = getStatusManager();
         for (StatusListener sl : sm.getCopyOfStatusListenerList()) {
-            if(!sl.isResetResistant()) {
+            if (!sl.isResetResistant()) {
                 sm.remove(sl);
             }
         }
@@ -254,29 +263,28 @@ public void resetTurboFilterList() {
         turboFilterList.clear();
     }
 
-    final FilterReply getTurboFilterChainDecision_0_3OrMore(final Marker marker, final Logger logger, final Level level,
-            final String format, final Object[] params, final Throwable t) {
+    final FilterReply getTurboFilterChainDecision_0_3OrMore(final Marker marker, final Logger logger, final Level level, final String format,
+                    final Object[] params, final Throwable t) {
         if (turboFilterList.size() == 0) {
             return FilterReply.NEUTRAL;
         }
         return turboFilterList.getTurboFilterChainDecision(marker, logger, level, format, params, t);
     }
 
-    final FilterReply getTurboFilterChainDecision_1(final Marker marker, final Logger logger, final Level level,
-            final String format, final Object param, final Throwable t) {
+    final FilterReply getTurboFilterChainDecision_1(final Marker marker, final Logger logger, final Level level, final String format, final Object param,
+                    final Throwable t) {
         if (turboFilterList.size() == 0) {
             return FilterReply.NEUTRAL;
         }
         return turboFilterList.getTurboFilterChainDecision(marker, logger, level, format, new Object[] { param }, t);
     }
 
-    final FilterReply getTurboFilterChainDecision_2(final Marker marker, final Logger logger, final Level level,
-            final String format, final Object param1, final Object param2, final Throwable t) {
+    final FilterReply getTurboFilterChainDecision_2(final Marker marker, final Logger logger, final Level level, final String format, final Object param1,
+                    final Object param2, final Throwable t) {
         if (turboFilterList.size() == 0) {
             return FilterReply.NEUTRAL;
         }
-        return turboFilterList.getTurboFilterChainDecision(marker, logger, level, format,
-                new Object[] { param1, param2 }, t);
+        return turboFilterList.getTurboFilterChainDecision(marker, logger, level, format, new Object[] { param1, param2 }, t);
     }
 
     // === start listeners ==============================================
@@ -340,10 +348,21 @@ public void start() {
     }
 
     public void stop() {
-        reset();
-        fireOnStop();
-        resetAllListeners();
-        super.stop();
+        if (!isStarted())
+            return;
+
+        try {
+            configurationLock.lock();
+            if (!isStarted())
+                return;
+
+            reset();
+            fireOnStop();
+            resetAllListeners();
+            super.stop();
+        } finally {
+            configurationLock.unlock();
+        }
     }
 
     /**
@@ -395,7 +414,6 @@ public List<String> getFrameworkPackages() {
         return frameworkPackages;
     }
 
-
     @Override
     public void setSequenceNumberGenerator(SequenceNumberGenerator sng) {
         this.sequenceNumberGenerator = sng;
@@ -411,7 +429,7 @@ public MDCAdapter getMDCAdapter() {
     }
 
     public void setMDCAdapter(MDCAdapter anAdapter) {
-        if(this.mdcAdapter !=  null) {
+        if (this.mdcAdapter != null) {
             StatusManager sm = getStatusManager();
             sm.add(new WarnStatus("mdcAdapter being reset a second time", this));
         }
diff --git a/logback-classic/src/main/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTask.java b/logback-classic/src/main/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTask.java
index 74f0304683..2a2b6767f2 100755
--- a/logback-classic/src/main/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTask.java
+++ b/logback-classic/src/main/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTask.java
@@ -30,7 +30,7 @@
 import ch.qos.logback.core.status.StatusUtil;
 
 import static ch.qos.logback.core.spi.ConfigurationEvent.newConfigurationChangeDetectorRunningEvent;
-import static ch.qos.logback.core.spi.ConfigurationEvent.newConfigurationEndedEvent;
+import static ch.qos.logback.core.spi.ConfigurationEvent.newConfigurationEndedSuccessfullyEvent;
 
 public class ReconfigureOnChangeTask extends ContextAwareBase implements Runnable {
 
@@ -92,6 +92,7 @@ private void performXMLConfiguration(LoggerContext lc, URL mainConfigurationURL)
         StatusUtil statusUtil = new StatusUtil(context);
         Model failsafeTop = jc.recallSafeConfiguration();
         URL mainURL = ConfigurationWatchListUtil.getMainWatchURL(context);
+        addInfo("Resetting loggerContext ["+lc.getName()+"]");
         lc.reset();
         long threshold = System.currentTimeMillis();
         try {
@@ -129,8 +130,7 @@ private void fallbackConfiguration(LoggerContext lc, Model failsafeTop, URL main
                 joranConfigurator.processModel(failsafeTop);
                 addInfo(RE_REGISTERING_PREVIOUS_SAFE_CONFIGURATION);
                 joranConfigurator.registerSafeConfiguration(failsafeTop);
-                context.fireConfigurationEvent(newConfigurationEndedEvent(this));
-                addInfo("after registerSafeConfiguration");
+                context.fireConfigurationEvent(newConfigurationEndedSuccessfullyEvent(this));
             } catch (Exception e) {
                 addError("Unexpected exception thrown by a configuration considered safe.", e);
             }
diff --git a/logback-classic/src/main/java/ch/qos/logback/classic/joran/SerializedModelConfigurator.java b/logback-classic/src/main/java/ch/qos/logback/classic/joran/SerializedModelConfigurator.java
index 9bf7c03f16..2cc7f20868 100644
--- a/logback-classic/src/main/java/ch/qos/logback/classic/joran/SerializedModelConfigurator.java
+++ b/logback-classic/src/main/java/ch/qos/logback/classic/joran/SerializedModelConfigurator.java
@@ -37,6 +37,7 @@
 import java.io.InputStream;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.util.concurrent.locks.ReentrantLock;
 
 import static ch.qos.logback.core.CoreConstants.MODEL_CONFIG_FILE_EXTENSION;
 
@@ -81,8 +82,12 @@ private void configureByResource(URL url) {
             mc2mhl.link(defaultProcessor);
 
             // disallow simultaneous configurations of the same context
-            synchronized (context.getConfigurationLock()) {
+            ReentrantLock configurationLock   = context.getConfigurationLock();
+            try {
+                configurationLock.lock();
                 defaultProcessor.process(model);
+            } finally {
+                configurationLock.unlock();
             }
         } else {
             throw new LogbackException(
diff --git a/logback-classic/src/test/java/ch/qos/logback/classic/Logback1551.java b/logback-classic/src/test/java/ch/qos/logback/classic/Logback1551.java
new file mode 100644
index 0000000000..85dbfd7746
--- /dev/null
+++ b/logback-classic/src/test/java/ch/qos/logback/classic/Logback1551.java
@@ -0,0 +1,81 @@
+/*
+ * Logback: the reliable, generic, fast and flexible logging framework.
+ * Copyright (C) 1999-2024, QOS.ch. All rights reserved.
+ *
+ * This program and the accompanying materials are dual-licensed under
+ * either the terms of the Eclipse Public License v1.0 as published by
+ * the Eclipse Foundation
+ *
+ *   or (per the licensee's choosing)
+ *
+ * under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation.
+ */
+
+package ch.qos.logback.classic;
+
+import ch.qos.logback.core.util.Duration;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+public class Logback1551 {
+    LoggerContext lc;
+
+    @BeforeEach
+    public void setUp() throws Exception {
+        lc = new LoggerContext();
+        lc.setName("x");
+    }
+    @Test
+    public void testConcurrentModificationScheduledTasks() {
+        ScheduledExecutorService scheduledExecutorService = lc.getScheduledExecutorService();
+        Duration duration = Duration.buildByMilliseconds(10);
+
+        Runnable runnable = new Runnable() {
+            public void run() {
+                try {
+                    Thread.sleep(100);
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        };
+        ScheduledFuture<?> scheduledFuture = scheduledExecutorService.scheduleAtFixedRate(runnable,
+                duration.getMilliseconds(), duration.getMilliseconds(), TimeUnit.MILLISECONDS);
+
+        lc.addScheduledFuture(scheduledFuture);
+        int THREAD_COUNT = 20;
+        Thread[] threads = new Thread[THREAD_COUNT];
+
+        for (int i = 0; i < THREAD_COUNT; i++) {
+            threads[i] = new Thread(new CancelRunnable(lc));
+            threads[i].start();
+        }
+
+        Arrays.stream(threads).forEach(t-> {
+            try {
+                t.join();
+            } catch (InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+        });
+
+    }
+
+    private class CancelRunnable implements Runnable {
+        LoggerContext lc;
+        public CancelRunnable(LoggerContext lc) {
+            this.lc = lc;
+        }
+
+        @Override
+        public void run() {
+            lc.cancelScheduledTasks();
+        }
+    }
+}
diff --git a/logback-classic/src/test/java/ch/qos/logback/classic/LoggerContextTest.java b/logback-classic/src/test/java/ch/qos/logback/classic/LoggerContextTest.java
index 5d973a40cd..c4d5d64ca8 100644
--- a/logback-classic/src/test/java/ch/qos/logback/classic/LoggerContextTest.java
+++ b/logback-classic/src/test/java/ch/qos/logback/classic/LoggerContextTest.java
@@ -1,36 +1,30 @@
 /**
  * Logback: the reliable, generic, fast and flexible logging framework.
  * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
- *
+ * <p>
  * This program and the accompanying materials are dual-licensed under
  * either the terms of the Eclipse Public License v1.0 as published by
  * the Eclipse Foundation
- *
- *   or (per the licensee's choosing)
- *
+ * <p>
+ * or (per the licensee's choosing)
+ * <p>
  * under the terms of the GNU Lesser General Public License version 2.1
  * as published by the Free Software Foundation.
  */
 package ch.qos.logback.classic;
 
-import static ch.qos.logback.core.CoreConstants.FA_FILENAME_COLLISION_MAP;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
-
-import java.util.Map;
-
-import org.junit.jupiter.api.BeforeEach;
-
 import ch.qos.logback.classic.turbo.NOPTurboFilter;
 import ch.qos.logback.core.CoreConstants;
 import ch.qos.logback.core.rolling.helper.FileNamePattern;
 import ch.qos.logback.core.status.StatusManager;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import java.util.Map;
+
+import static ch.qos.logback.core.CoreConstants.FA_FILENAME_COLLISION_MAP;
+import static org.junit.jupiter.api.Assertions.*;
+
 public class LoggerContextTest {
     LoggerContext lc;
 
@@ -251,8 +245,8 @@ public void collisionMapsPostReset() {
         assertNotNull(fileCollisions);
         assertTrue(fileCollisions.isEmpty());
 
-        Map<String, FileNamePattern> filenamePatternCollisionMap = (Map<String, FileNamePattern>) lc
-                .getObject(CoreConstants.RFA_FILENAME_PATTERN_COLLISION_MAP);
+        Map<String, FileNamePattern> filenamePatternCollisionMap = (Map<String, FileNamePattern>) lc.getObject(
+                        CoreConstants.RFA_FILENAME_PATTERN_COLLISION_MAP);
         assertNotNull(filenamePatternCollisionMap);
         assertTrue(filenamePatternCollisionMap.isEmpty());
     }
diff --git a/logback-classic/src/test/java/ch/qos/logback/classic/joran/ChangeDetectedListener.java b/logback-classic/src/test/java/ch/qos/logback/classic/joran/ChangeDetectedListener.java
index 98f02fb5bf..aa070ee502 100644
--- a/logback-classic/src/test/java/ch/qos/logback/classic/joran/ChangeDetectedListener.java
+++ b/logback-classic/src/test/java/ch/qos/logback/classic/joran/ChangeDetectedListener.java
@@ -33,7 +33,7 @@ class ChangeDetectedListener  implements ConfigurationEventListener {
     public void listen(ConfigurationEvent configurationEvent) {
         switch (configurationEvent.getEventType()) {
         case CHANGE_DETECTED:
-            System.out.println(this.toString() + "#listen Change detected" + " count="+countDownLatch.getCount());
+            System.out.println(this.toString() + "#listen Change detected " + configurationEvent +" count="+countDownLatch.getCount());
 
             countDownLatch.countDown();
             Object data = configurationEvent.getData();
diff --git a/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigurationDoneListener.java b/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigurationDoneListener.java
index 856838969c..99f3d4b3a7 100644
--- a/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigurationDoneListener.java
+++ b/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigurationDoneListener.java
@@ -23,6 +23,7 @@ class ReconfigurationDoneListener implements ConfigurationEventListener {
     CountDownLatch countDownLatch;
 
     ReconfigureOnChangeTask roct;
+
     ReconfigurationDoneListener(CountDownLatch countDownLatch,  ReconfigureOnChangeTask aRoct) {
         this.countDownLatch = countDownLatch;
         this.roct = aRoct;
@@ -31,7 +32,7 @@ class ReconfigurationDoneListener implements ConfigurationEventListener {
     @Override
     public void listen(ConfigurationEvent configurationEvent) {
         switch (configurationEvent.getEventType()) {
-        case CONFIGURATION_ENDED:
+            case CONFIGURATION_ENDED_SUCCESSFULLY:
             if(roct == null) {
                 countDownLatch.countDown();
             } else {
diff --git a/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTaskTest.java b/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTaskTest.java
index 2fd79a6554..9e2cb11df0 100755
--- a/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTaskTest.java
+++ b/logback-classic/src/test/java/ch/qos/logback/classic/joran/ReconfigureOnChangeTaskTest.java
@@ -39,7 +39,6 @@
 import ch.qos.logback.core.status.WarnStatus;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.BeforeAll;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import ch.qos.logback.classic.Logger;
@@ -185,6 +184,7 @@ public void reconfigurationIsNotPossibleInTheAbsenceOfATopFile()
     @Test
     @Timeout(value = TIMEOUT, unit = TimeUnit.SECONDS)
     public void fallbackToSafe_FollowedByRecovery() throws IOException, JoranException, InterruptedException {
+        addInfo("Start fallbackToSafe_FollowedByRecovery", this);
         String path = CoreTestConstants.OUTPUT_DIR_PREFIX + "reconfigureOnChangeConfig_fallbackToSafe-" + diff + ".xml";
         File topLevelFile = new File(path);
         writeToFile(topLevelFile,
@@ -193,30 +193,33 @@ public void fallbackToSafe_FollowedByRecovery() throws IOException, JoranExcepti
         addResetResistantOnConsoleStatusListener();
         configure(topLevelFile);
 
-        long afterFirstConfiguration = System.currentTimeMillis();
         CountDownLatch changeDetectedLatch = registerChangeDetectedListener();
-        CountDownLatch configurationDoneLatch = registerNewReconfigurationDoneListener();
+        CountDownLatch configurationDoneLatch = registerNewReconfigurationDoneSuccessfullyListener();
 
         String badXML = "<configuration scan=\"true\" scanPeriod=\"5 millisecond\">\n" + "  <root></configuration>";
         writeToFile(topLevelFile, badXML);
         changeDetectedLatch.await();
         configurationDoneLatch.await();
-        addInfo("Woke from configurationDoneLatch.await()", this);
 
         statusChecker.assertContainsMatch(Status.ERROR, CoreConstants.XML_PARSING);
         statusChecker.assertContainsMatch(Status.WARN, FALLING_BACK_TO_SAFE_CONFIGURATION);
         statusChecker.assertContainsMatch(Status.INFO, RE_REGISTERING_PREVIOUS_SAFE_CONFIGURATION);
 
+        // clear required for checks down below
         loggerContext.getStatusManager().clear();
 
-        addInfo("after loggerContext.getStatusManager().clear() ", this);
-        CountDownLatch secondConfigEndedLatch = registerNewReconfigurationDoneListener();
+        addInfo("RECOVERY - Writing error-free config file  ", this);
+        CountDownLatch secondConfigEndedLatch = registerNewReconfigurationDoneSuccessfullyListener();
 
+        // recovery
         writeToFile(topLevelFile,
                 "<configuration scan=\"true\" scanPeriod=\"5 millisecond\"><root level=\"ERROR\"/></configuration> ");
 
-        secondConfigEndedLatch.await();
+
         try {
+            addInfo("Awaiting secondConfigEndedLatch ", this);
+            secondConfigEndedLatch.await(5, TimeUnit.SECONDS);
+            addInfo("after secondConfigEndedLatch.await ", this);
             statusChecker.assertIsErrorFree();
             statusChecker.containsMatch(DETECTED_CHANGE_IN_CONFIGURATION_FILES);
         } finally {
@@ -263,7 +266,7 @@ public void fallbackToSafeWithIncludedFile_FollowedByRecovery()
         System.out.println("===================================================");
 
         CountDownLatch changeDetectedLatch = registerChangeDetectedListener();
-        CountDownLatch configurationDoneLatch = registerNewReconfigurationDoneListener(roct);
+        CountDownLatch configurationDoneLatch = registerNewReconfigurationDoneSuccessfullyListener(roct);
 
         writeToFile(innerFile, "<included>\n<root>\n</included>");
         changeDetectedLatch.await();
@@ -276,7 +279,7 @@ public void fallbackToSafeWithIncludedFile_FollowedByRecovery()
 
         loggerContext.getStatusManager().clear();
 
-        CountDownLatch secondDoneLatch = registerNewReconfigurationDoneListener();
+        CountDownLatch secondDoneLatch = registerNewReconfigurationDoneSuccessfullyListener();
         writeToFile(innerFile, "<included><root level=\"ERROR\"/></included> ");
         secondDoneLatch.await();
 
@@ -285,11 +288,11 @@ public void fallbackToSafeWithIncludedFile_FollowedByRecovery()
 
     }
 
-    CountDownLatch registerNewReconfigurationDoneListener() {
-        return registerNewReconfigurationDoneListener(null);
+    CountDownLatch registerNewReconfigurationDoneSuccessfullyListener() {
+        return registerNewReconfigurationDoneSuccessfullyListener(null);
     }
 
-    CountDownLatch registerNewReconfigurationDoneListener(ReconfigureOnChangeTask roct) {
+    CountDownLatch registerNewReconfigurationDoneSuccessfullyListener(ReconfigureOnChangeTask roct) {
         CountDownLatch latch = new CountDownLatch(1);
         ReconfigurationDoneListener reconfigurationDoneListener = new ReconfigurationDoneListener(latch, roct);
         loggerContext.addConfigurationEventListener(reconfigurationDoneListener);
@@ -368,9 +371,6 @@ public void scan_LOGBACK_474() throws JoranException, IOException, InterruptedEx
         addResetResistantOnConsoleStatusListener();
         configure(file);
 
-        // ReconfigureOnChangeTask roct = waitForReconfigureOnChangeTaskToRun();
-        System.out.println(" ------------ creating ReconfigureOnChangeTaskHarness");
-
         int expectedResets = 2;
         ReconfigureOnChangeTaskHarness harness = new ReconfigureOnChangeTaskHarness(loggerContext, expectedResets);
 
diff --git a/logback-classic/src/test/java/ch/qos/logback/classic/spi/ContextListenerTest.java b/logback-classic/src/test/java/ch/qos/logback/classic/spi/ContextListenerTest.java
index 17a1f11c96..1dec87840f 100644
--- a/logback-classic/src/test/java/ch/qos/logback/classic/spi/ContextListenerTest.java
+++ b/logback-classic/src/test/java/ch/qos/logback/classic/spi/ContextListenerTest.java
@@ -26,47 +26,48 @@
 
 public class ContextListenerTest {
 
-    LoggerContext context;
+    LoggerContext loggerContext;
     BasicContextListener listener;
 
     @BeforeEach
     public void setUp() throws Exception {
-        context = new LoggerContext();
+        loggerContext = new LoggerContext();
+        loggerContext.start();
         listener = new BasicContextListener();
-        context.addListener(listener);
+        loggerContext.addListener(listener);
     }
 
     @Test
     public void testNotifyOnReset() {
-        context.reset();
+        loggerContext.reset();
         assertEquals(UpdateType.RESET, listener.updateType);
-        assertEquals(listener.context, context);
+        assertEquals(listener.context, loggerContext);
     }
 
     @Test
-    public void testNotifyOnStopResistant() {
+    public void testResistantListener_NotifyOnStop() {
         listener.setResetResistant(true);
-        context.stop();
+        loggerContext.stop();
         assertEquals(UpdateType.STOP, listener.updateType);
-        assertEquals(listener.context, context);
+        assertEquals(listener.context, loggerContext);
     }
 
     @Test
-    public void testNotifyOnStopNotResistant() {
-        context.stop();
+    public void testNotResistantListener_NotifyOnStop() {
+        loggerContext.stop();
         assertEquals(UpdateType.RESET, listener.updateType);
-        assertEquals(listener.context, context);
+        assertEquals(listener.context, loggerContext);
     }
 
     @Test
     public void testNotifyOnStart() {
-        context.start();
+        loggerContext.start();
         assertEquals(UpdateType.START, listener.updateType);
-        assertEquals(listener.context, context);
+        assertEquals(listener.context, loggerContext);
     }
 
     void checkLevelChange(String loggerName, Level level) {
-        Logger logger = context.getLogger(loggerName);
+        Logger logger = loggerContext.getLogger(loggerName);
         logger.setLevel(level);
 
         assertEquals(UpdateType.LEVEL_CHANGE, listener.updateType);
diff --git a/logback-core/src/main/java/ch/qos/logback/core/Context.java b/logback-core/src/main/java/ch/qos/logback/core/Context.java
index 0a8b57af70..eb35feaa68 100644
--- a/logback-core/src/main/java/ch/qos/logback/core/Context.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/Context.java
@@ -18,6 +18,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.locks.ReentrantLock;
 
 import ch.qos.logback.core.spi.ConfigurationEvent;
 import ch.qos.logback.core.spi.ConfigurationEventListener;
@@ -107,7 +108,7 @@ public interface Context extends PropertyContainer {
     /**
      * Object used for synchronization purposes. INTENDED FOR INTERNAL USAGE.
      */
-    Object getConfigurationLock();
+    ReentrantLock getConfigurationLock();
 
     /**
      * Returns the ScheduledExecutorService for this context.
@@ -169,12 +170,17 @@ default ExecutorService getAlternateExecutorService() {
      * <p>The propagation of {@link ConfigurationEvent configuration events} is intended for internal testing
      * as well as some coordination between configurators.</p>
      *
-     *
      * @param listener
      * @since 1.3.6/1.4.6
      */
     void addConfigurationEventListener(ConfigurationEventListener listener);
 
+    /**
+     * Remove an existing ConfigurationEventListener
+     * @param listener
+     * @since 1.5.7
+     */
+    default void removeConfigurationEventListener(ConfigurationEventListener listener) {};
     /**
      * Fire {@link ConfigurationEvent} by invoking {@link #addConfigurationEventListener registered listeners}.
      *
diff --git a/logback-core/src/main/java/ch/qos/logback/core/ContextBase.java b/logback-core/src/main/java/ch/qos/logback/core/ContextBase.java
index 0c9920dacb..8bd4c148f9 100755
--- a/logback-core/src/main/java/ch/qos/logback/core/ContextBase.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/ContextBase.java
@@ -23,12 +23,12 @@
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.*;
+import java.util.concurrent.locks.ReentrantLock;
 
 import ch.qos.logback.core.rolling.helper.FileNamePattern;
 import ch.qos.logback.core.spi.ConfigurationEvent;
 import ch.qos.logback.core.spi.ConfigurationEventListener;
 import ch.qos.logback.core.spi.LifeCycle;
-import ch.qos.logback.core.spi.LogbackLock;
 import ch.qos.logback.core.spi.SequenceNumberGenerator;
 import ch.qos.logback.core.status.InfoStatus;
 import ch.qos.logback.core.status.StatusManager;
@@ -47,7 +47,7 @@ public class ContextBase implements Context, LifeCycle {
     Map<String, String> propertyMap = new HashMap<String, String>();
     Map<String, Object> objectMap = new ConcurrentHashMap<>();
 
-    LogbackLock configurationLock = new LogbackLock();
+    protected ReentrantLock configurationLock = new ReentrantLock();
 
     final private List<ConfigurationEventListener> configurationEventListenerList = new CopyOnWriteArrayList<>();
 
@@ -61,7 +61,8 @@ public class ContextBase implements Context, LifeCycle {
     private LifeCycleManager lifeCycleManager;
     private SequenceNumberGenerator sequenceNumberGenerator;
 
-    private boolean started;
+    // 'started' is used to mitigate race conditions in stop() and possibly other methods, hence the volatile qualifier.
+    private volatile boolean started;
 
     public ContextBase() {
         initCollisionMaps();
@@ -223,7 +224,7 @@ public long getBirthTime() {
         return birthTime;
     }
 
-    public Object getConfigurationLock() {
+    public ReentrantLock getConfigurationLock() {
         return configurationLock;
     }
 
@@ -336,9 +337,13 @@ public void addConfigurationEventListener(ConfigurationEventListener listener) {
         configurationEventListenerList.add(listener);
     }
 
+    @Override
+    public void removeConfigurationEventListener(ConfigurationEventListener listener) {
+        configurationEventListenerList.remove(listener);
+    }
+
     @Override
     public void fireConfigurationEvent(ConfigurationEvent configurationEvent) {
-        //System.out.println("xxxx fireConfigurationEvent  of "+configurationEvent);
         configurationEventListenerList.forEach( l -> l.listen(configurationEvent));
     }
 }
diff --git a/logback-core/src/main/java/ch/qos/logback/core/joran/GenericXMLConfigurator.java b/logback-core/src/main/java/ch/qos/logback/core/joran/GenericXMLConfigurator.java
index e0c66d388c..3680903a31 100755
--- a/logback-core/src/main/java/ch/qos/logback/core/joran/GenericXMLConfigurator.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/joran/GenericXMLConfigurator.java
@@ -12,8 +12,7 @@
 package ch.qos.logback.core.joran;
 
 import static ch.qos.logback.core.CoreConstants.SAFE_JORAN_CONFIGURATION;
-import static ch.qos.logback.core.spi.ConfigurationEvent.newConfigurationEndedEvent;
-import static ch.qos.logback.core.spi.ConfigurationEvent.newConfigurationStartedEvent;
+import static ch.qos.logback.core.spi.ConfigurationEvent.*;
 
 import java.io.File;
 import java.io.FileInputStream;
@@ -22,6 +21,7 @@
 import java.net.URL;
 import java.net.URLConnection;
 import java.util.List;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.xml.sax.InputSource;
 
@@ -182,8 +182,11 @@ public final void doConfigure(final InputSource inputSource) throws JoranExcepti
         if (statusUtil.noXMLParsingErrorsOccurred(threshold)) {
             addInfo("Registering current configuration as safe fallback point");
             registerSafeConfiguration(top);
+            context.fireConfigurationEvent(newConfigurationEndedSuccessfullyEvent(this));
+        } else {
+            context.fireConfigurationEvent(newConfigurationEndedWithXMLParsingErrorsEvent(this));
         }
-        context.fireConfigurationEvent(newConfigurationEndedEvent(this));
+
 
     }
 
@@ -212,8 +215,13 @@ public void processModel(Model model) {
         addModelHandlerAssociations(defaultProcessor);
 
         // disallow simultaneous configurations of the same context
-        synchronized (context.getConfigurationLock()) {
+        ReentrantLock configurationLock   = context.getConfigurationLock();
+
+        try {
+            configurationLock.lock();
             defaultProcessor.process(model);
+        } finally {
+            configurationLock.unlock();
         }
     }
 
diff --git a/logback-core/src/main/java/ch/qos/logback/core/model/processor/ShutdownHookModelHandler.java b/logback-core/src/main/java/ch/qos/logback/core/model/processor/ShutdownHookModelHandler.java
index dc14303a45..6677571e42 100755
--- a/logback-core/src/main/java/ch/qos/logback/core/model/processor/ShutdownHookModelHandler.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/model/processor/ShutdownHookModelHandler.java
@@ -20,6 +20,7 @@
 import ch.qos.logback.core.hook.ShutdownHookBase;
 import ch.qos.logback.core.model.Model;
 import ch.qos.logback.core.model.ShutdownHookModel;
+import ch.qos.logback.core.util.ContextUtil;
 import ch.qos.logback.core.util.DynamicClassLoadingException;
 import ch.qos.logback.core.util.IncompatibleClassException;
 import ch.qos.logback.core.util.OptionHelper;
@@ -87,11 +88,8 @@ public void postHandle(ModelInterpretationContext mic, Model model) throws Model
         if (o != hook) {
             addWarn("The object on the top the of the stack is not the hook object pushed earlier.");
         } else {
-            Thread hookThread = new Thread(hook, "Logback shutdown hook [" + context.getName() + "]");
-            addInfo("Registering shutdown hook with JVM runtime.");
-            context.putObject(CoreConstants.SHUTDOWN_HOOK_THREAD, hookThread);
-            Runtime.getRuntime().addShutdownHook(hookThread);
-
+            ContextUtil contextUtil = new ContextUtil(context);
+            contextUtil.addOrReplaceShutdownHook(hook);
             mic.popObject();
         }
     }
diff --git a/logback-core/src/main/java/ch/qos/logback/core/spi/ConfigurationEvent.java b/logback-core/src/main/java/ch/qos/logback/core/spi/ConfigurationEvent.java
index d019309dcd..17a3504db1 100644
--- a/logback-core/src/main/java/ch/qos/logback/core/spi/ConfigurationEvent.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/spi/ConfigurationEvent.java
@@ -32,7 +32,8 @@ public enum EventType {
         CHANGE_DETECTOR_RUNNING,
         CHANGE_DETECTED,
         CONFIGURATION_STARTED,
-        CONFIGURATION_ENDED;
+        CONFIGURATION_ENDED_SUCCESSFULLY,
+        CONFIGURATION_ENDED_WITH_XML_PARSING_ERRORS;
     }
     final EventType eventType;
     final Object data;
@@ -61,10 +62,12 @@ static public ConfigurationEvent newConfigurationChangeDetectedEvent(Object data
     static public ConfigurationEvent newConfigurationStartedEvent(Object data) {
         return new ConfigurationEvent(EventType.CONFIGURATION_STARTED, data);
     }
-    static public ConfigurationEvent newConfigurationEndedEvent(Object data) {
-        return new ConfigurationEvent(EventType.CONFIGURATION_ENDED, data);
+    static public ConfigurationEvent newConfigurationEndedSuccessfullyEvent(Object data) {
+        return new ConfigurationEvent(EventType.CONFIGURATION_ENDED_SUCCESSFULLY, data);
+    }
+    static public ConfigurationEvent newConfigurationEndedWithXMLParsingErrorsEvent(Object data) {
+        return new ConfigurationEvent(EventType.CONFIGURATION_ENDED_WITH_XML_PARSING_ERRORS, data);
     }
-
     public EventType getEventType() {
         return eventType;
     }
diff --git a/logback-core/src/main/java/ch/qos/logback/core/util/ContextUtil.java b/logback-core/src/main/java/ch/qos/logback/core/util/ContextUtil.java
index ac9c63fcbe..4ad3abb283 100755
--- a/logback-core/src/main/java/ch/qos/logback/core/util/ContextUtil.java
+++ b/logback-core/src/main/java/ch/qos/logback/core/util/ContextUtil.java
@@ -22,6 +22,8 @@
 import java.util.Properties;
 
 import ch.qos.logback.core.Context;
+import ch.qos.logback.core.CoreConstants;
+import ch.qos.logback.core.hook.ShutdownHook;
 import ch.qos.logback.core.rolling.helper.FileNamePattern;
 import ch.qos.logback.core.spi.ContextAwareBase;
 
@@ -73,4 +75,27 @@ public void addFrameworkPackage(List<String> frameworkPackages, String packageNa
         }
     }
 
+    /**
+     * Add a shutdown hook thread with the JVM runtime.
+     *
+     * If a previous shutdown hook thread was registered, it is replaced.
+     * @param hook
+     * @since 1.5.7
+     */
+    public void addOrReplaceShutdownHook(ShutdownHook hook) {
+        Runtime runtime = Runtime.getRuntime();
+
+        Thread oldShutdownHookTread = (Thread) context.getObject(CoreConstants.SHUTDOWN_HOOK_THREAD);
+        if(oldShutdownHookTread != null) {
+            addInfo("Removing old shutdown hook from JVM runtime");
+            runtime.removeShutdownHook(oldShutdownHookTread);
+        }
+
+        Thread hookThread = new Thread(hook, "Logback shutdown hook [" + context.getName() + "]");
+        addInfo("Registering shutdown hook with JVM runtime.");
+        context.putObject(CoreConstants.SHUTDOWN_HOOK_THREAD, hookThread);
+        runtime.addShutdownHook(hookThread);
+
+    }
+
 }
diff --git a/logback-core/src/test/java/ch/qos/logback/core/util/ContextUtilAddOrReplaceShutdownHookTest.java b/logback-core/src/test/java/ch/qos/logback/core/util/ContextUtilAddOrReplaceShutdownHookTest.java
new file mode 100644
index 0000000000..2978832345
--- /dev/null
+++ b/logback-core/src/test/java/ch/qos/logback/core/util/ContextUtilAddOrReplaceShutdownHookTest.java
@@ -0,0 +1,67 @@
+/*
+ * Logback: the reliable, generic, fast and flexible logging framework.
+ * Copyright (C) 1999-2024, QOS.ch. All rights reserved.
+ *
+ * This program and the accompanying materials are dual-licensed under
+ * either the terms of the Eclipse Public License v1.0 as published by
+ * the Eclipse Foundation
+ *
+ *   or (per the licensee's choosing)
+ *
+ * under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation.
+ */
+
+package ch.qos.logback.core.util;
+
+import ch.qos.logback.core.Context;
+import ch.qos.logback.core.ContextBase;
+import ch.qos.logback.core.hook.ShutdownHookBase;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Given the code executed in a shutdown hook is the last bit of code that is executed
+ * before the JVM exits, there is no way to test that a shutdown hook has been removed or
+ * is active.
+ *
+ * As such, this test cannot be automated.
+ */
+@Disabled
+class ContextUtilAddOrReplaceShutdownHookTest {
+
+    Context context = new ContextBase();
+    ContextUtil contextUtil = new ContextUtil(context);
+
+    @Test
+    public void smoke() {
+
+        contextUtil.addOrReplaceShutdownHook(new HelloShutdownHookHook(2));
+        contextUtil.addOrReplaceShutdownHook(new HelloShutdownHookHook(3));
+        contextUtil.addOrReplaceShutdownHook(new HelloShutdownHookHook(5));
+        // expect to see
+        // HelloShutdownHookHook{number=5}
+    }
+
+    static class HelloShutdownHookHook extends ShutdownHookBase {
+
+        int number;
+
+
+        public HelloShutdownHookHook(int number) {
+            this.number = number;
+
+        }
+
+        @Override
+        public void run() {
+            System.out.println(this);
+        }
+
+        @Override
+        public String toString() {
+            return "HelloShutdownHookHook{" + "number=" + number + '}';
+        }
+    }
+
+}
\ No newline at end of file