diff --git a/Furious/Frozenlib/Mixins.py b/Furious/Frozenlib/Mixins.py
index a13080d..3985439 100644
--- a/Furious/Frozenlib/Mixins.py
+++ b/Furious/Frozenlib/Mixins.py
@@ -215,23 +215,30 @@ class Mixins:
             """Handle cleanup all for the cleanup on exit."""
             Mixins.CleanupOnExit.ObjectsPool.prune(Mixins.qObjectIsValid)
 
-            for ob in list(Mixins.CleanupOnExit.ObjectsPool):
-                assert isinstance(ob, Mixins.CleanupOnExit)
+            try:
+                for ob in list(Mixins.CleanupOnExit.ObjectsPool):
+                    assert isinstance(ob, Mixins.CleanupOnExit)
 
-                if ob.uniqueCleanup:
-                    obtype = str(type(ob))
+                    if ob.uniqueCleanup:
+                        obtype = str(type(ob))
 
-                    if not Mixins.CleanupOnExit.VisitedType.get(obtype, False):
-                        ob.cleanup()
+                        if Mixins.CleanupOnExit.VisitedType.get(obtype, False):
+                            continue
 
                         Mixins.CleanupOnExit.VisitedType[obtype] = True
-                    else:
-                        pass
-                else:
-                    ob.cleanup()
 
-            Mixins.CleanupOnExit.ObjectsPool.clear()
-            Mixins.CleanupOnExit.VisitedType.clear()
+                    try:
+                        ob.cleanup()
+                    except Exception:
+                        # Any non-exit exceptions
+
+                        # Cleanup is an isolation boundary. One failed owner
+                        # must not prevent unrelated resources from being
+                        # released during application shutdown.
+                        logger.exception(f'cleanup failed for {type(ob).__name__}')
+            finally:
+                Mixins.CleanupOnExit.ObjectsPool.clear()
+                Mixins.CleanupOnExit.VisitedType.clear()
 
     class QSetDisabledContext:
         """Manage the q set disabled context."""
diff --git a/Furious/Plugins/Registry.py b/Furious/Plugins/Registry.py
index 24a309d..18d2e43 100644
--- a/Furious/Plugins/Registry.py
+++ b/Furious/Plugins/Registry.py
@@ -1334,10 +1334,20 @@ class _PluginRegistryManager:
         """Build a registry with host plugins taking discovery precedence."""
         registry = PluginRegistry()
 
-        for pluginType in pluginTypes:
-            registry.register(pluginType())
+        try:
+            for pluginType in pluginTypes:
+                registry.register(pluginType())
 
-        registry.discover()
+            registry.discover()
+        except Exception:
+            # Any non-exit exceptions
+
+            # The manager publishes the registry only after this method
+            # succeeds. Release plugins initialized earlier in this attempt
+            # before abandoning the unpublished registry.
+            registry.shutdown()
+
+            raise
 
         return registry
 
diff --git a/tests/test_frozenlib.py b/tests/test_frozenlib.py
index c8edb1a..516a118 100644
--- a/tests/test_frozenlib.py
+++ b/tests/test_frozenlib.py
@@ -123,6 +123,47 @@ class FrozenlibQtContextTest(unittest.TestCase):
             processQtEvents()
 
 
+class CleanupOnExitTest(unittest.TestCase):
+    """Verify application cleanup isolates independently owned resources."""
+
+    def testCleanupFailureDoesNotSkipLaterOwners(self):
+        """Continue cleanup after one participant raises and reset registry state."""
+        calls = []
+        poolType = type(Mixins.CleanupOnExit.ObjectsPool)
+
+        class Participant(Mixins.CleanupOnExit):
+            def __init__(self, name: str, raises=False):
+                self.name = name
+                self.raises = raises
+
+                super().__init__(uniqueCleanup=False)
+
+            def cleanup(self):
+                calls.append(self.name)
+
+                if self.raises:
+                    raise RuntimeError('cleanup fixture')
+
+        with mock.patch.object(
+            Mixins.CleanupOnExit,
+            'ObjectsPool',
+            poolType(),
+        ), mock.patch.object(Mixins.CleanupOnExit, 'VisitedType', {}):
+            participants = (
+                Participant('first'),
+                Participant('failing', raises=True),
+                Participant('last'),
+            )
+
+            with self.assertLogs('Furious.Frozenlib.Mixins', level='ERROR'):
+                Mixins.CleanupOnExit.cleanupAll()
+
+            self.assertEqual(calls, ['first', 'failing', 'last'])
+            self.assertEqual(len(Mixins.CleanupOnExit.ObjectsPool), 0)
+            self.assertEqual(Mixins.CleanupOnExit.VisitedType, {})
+            self.assertEqual(len(participants), 3)
+
+
 class FrozenlibUtilityTest(unittest.TestCase):
     """Verify bounded caches, commands, throttling, and dual-stack probes."""
 
diff --git a/tests/test_plugin_architecture.py b/tests/test_plugin_architecture.py
index 6367a6c..12e7f1d 100644
--- a/tests/test_plugin_architecture.py
+++ b/tests/test_plugin_architecture.py
@@ -266,6 +266,41 @@ class PluginRegistryManagerTest(unittest.TestCase):
             with self.assertRaisesRegex(ValueError, 'already registered'):
                 PluginRegistryModule.initializePluginRegistry((ConflictingPlugin,))
 
+    def testFailedInitialCreationShutsDownEarlierHostPlugins(self):
+        """Release initialized plugins when a later host plugin fails."""
+        initializedPlugin = FixturePlugin()
+
+        class InitializedPluginType:
+            """Return the observable plugin instance owned by this test."""
+
+            def __new__(cls):
+                return initializedPlugin
+
+        class FailingPluginType:
+            """Fail before the process registry can be published."""
+
+            def __new__(cls):
+                raise RuntimeError('host plugin construction failed')
+
+        with mock.patch.object(PluginRegistry, 'discover') as discover:
+            with self.assertRaisesRegex(
+                RuntimeError,
+                'host plugin construction failed',
+            ):
+                PluginRegistryModule.initializePluginRegistry(
+                    (InitializedPluginType, FailingPluginType)
+                )
+
+        self.assertEqual(initializedPlugin.initialized, 1)
+        self.assertEqual(initializedPlugin.stopped, 1)
+        discover.assert_not_called()
+
+        with mock.patch.object(PluginRegistry, 'discover') as discover:
+            registry = PluginRegistryModule.initializePluginRegistry()
+            self.addCleanup(registry.shutdown)
+
+        discover.assert_called_once_with()
+
 
 class PluginRegistryTest(unittest.TestCase):
     """Exercise capability dispatch without the process-wide registry."""