diff --git a/influxdb_client/_sync/api_client.py b/influxdb_client/_sync/api_client.py
index f61ef26c..7100fba2 100644
--- a/influxdb_client/_sync/api_client.py
+++ b/influxdb_client/_sync/api_client.py
@@ -81,13 +81,30 @@ def __init__(self, configuration=None, header_name=None, header_value=None,
 
     def __del__(self):
         """Dispose pools."""
-        self._signout()
-        if self._pool:
-            self._pool.close()
-            self._pool.join()
+        # During interpreter shutdown, attributes and imported services can already be cleared.
+        # A finalizer must not let those teardown details escape as an ignored exception.
+        try:
+            if getattr(self, 'configuration', None) is not None:
+                self._signout()
+        except Exception:
+            pass
+
+        pool = getattr(self, '_pool', None)
+        if pool:
+            try:
+                pool.close()
+                pool.join()
+            except Exception:
+                pass
             self._pool = None
-        if self.rest_client and self.rest_client.pool_manager and hasattr(self.rest_client.pool_manager, 'clear'):
-            self.rest_client.pool_manager.clear()
+
+        rest_client = getattr(self, 'rest_client', None)
+        pool_manager = getattr(rest_client, 'pool_manager', None)
+        if hasattr(pool_manager, 'clear'):
+            try:
+                pool_manager.clear()
+            except Exception:
+                pass
 
     @property
     def pool(self):
diff --git a/tests/test_InfluxDBClientAuthorization.py b/tests/test_InfluxDBClientAuthorization.py
index f828748d..2775f07f 100644
--- a/tests/test_InfluxDBClientAuthorization.py
+++ b/tests/test_InfluxDBClientAuthorization.py
@@ -1,8 +1,10 @@
 import unittest
+from unittest.mock import Mock
 
 import httpretty
 
 from influxdb_client import InfluxDBClient
+from influxdb_client._sync.api_client import ApiClient
 
 
 class InfluxDBClientAuthorization(unittest.TestCase):
@@ -10,6 +12,7 @@ class InfluxDBClientAuthorization(unittest.TestCase):
     def setUp(self) -> None:
         httpretty.enable()
         httpretty.reset()
+        self.influxdb_client = None
 
     def tearDown(self) -> None:
         if self.influxdb_client:
@@ -35,7 +38,10 @@ def test_session_request(self):
 
         self.assertEqual(2, len(httpretty.httpretty.latest_requests))
         # basic auth header
-        self.assertEqual('Basic bXktdXNlcm5hbWU6bXktcGFzc3dvcmQ=', httpretty.httpretty.latest_requests[0].headers['Authorization'])
+        self.assertEqual(
+            'Basic bXktdXNlcm5hbWU6bXktcGFzc3dvcmQ=',
+            httpretty.httpretty.latest_requests[0].headers['Authorization'],
+        )
         # cookie header
         self.assertEqual('session=xyz', httpretty.httpretty.latest_requests[1].headers['Cookie'])
         self.assertIsNotNone(self.influxdb_client.api_client.cookie)
@@ -44,3 +50,49 @@ def test_session_request(self):
         self.influxdb_client.close()
 
         self.assertEqual(3, len(httpretty.httpretty.latest_requests))
+
+    def test_api_client_finalizer_ignores_partially_torn_down_state(self):
+        api_client = ApiClient()
+        del api_client.configuration
+        del api_client.rest_client
+
+        api_client.__del__()
+
+    def test_api_client_finalizer_cleans_pools_when_signout_fails(self):
+        api_client = ApiClient()
+        api_client._signout = Mock(side_effect=RuntimeError('session service unavailable'))
+        pool = api_client._pool = Mock()
+        manager = api_client.rest_client.pool_manager = Mock()
+
+        api_client.__del__()
+
+        api_client._signout.assert_called_once_with()
+        pool.close.assert_called_once_with()
+        pool.join.assert_called_once_with()
+        self.assertIsNone(api_client._pool)
+        manager.clear.assert_called_once_with()
+
+    def test_api_client_finalizer_clears_http_pool_when_thread_pool_cleanup_fails(self):
+        for operation in ('close', 'join'):
+            with self.subTest(operation=operation):
+                api_client = ApiClient()
+                api_client._signout = Mock()
+                pool = api_client._pool = Mock()
+                getattr(pool, operation).side_effect = RuntimeError('pool already shut down')
+                manager = api_client.rest_client.pool_manager = Mock()
+
+                api_client.__del__()
+
+                getattr(pool, operation).assert_called_once_with()
+                self.assertIsNone(api_client._pool)
+                manager.clear.assert_called_once_with()
+
+    def test_api_client_finalizer_ignores_http_pool_cleanup_failure(self):
+        api_client = ApiClient()
+        api_client._signout = Mock()
+        manager = api_client.rest_client.pool_manager = Mock()
+        manager.clear.side_effect = RuntimeError('HTTP pool already shut down')
+
+        api_client.__del__()
+
+        manager.clear.assert_called_once_with()