diff --git a/tests/test_api.py b/tests/test_api.py
index d7bc416..c29f98e 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -38,6 +38,9 @@ class APITestCase(AioHTTPTestCase):
         return app
 
     async def tearDownAsync(self):
+        # Close every thread's connection first: Windows refuses to delete
+        # an open database file, and executor threads hold connections too.
+        self.api.db.close_all()
         for path in (
             self._temp_db.name,
             self._temp_db.name + "-wal",
diff --git a/tests/test_api_core.py b/tests/test_api_core.py
index 86d4ca7..2d534e7 100644
--- a/tests/test_api_core.py
+++ b/tests/test_api_core.py
@@ -372,6 +372,7 @@ class CoreRoutesTestCase(AioHTTPTestCase):
         return app
 
     async def tearDownAsync(self):
+        self.api.db.close_all()
         shutil.rmtree(self.tmpdir, ignore_errors=True)
 
     def _fake_root(self):
@@ -557,6 +558,7 @@ class TestInstanceHelpers(FolderPathsFixture):
         super().setUp()
         self.api = PromptManagerAPI()
         self.api.db = PromptDatabase(os.path.join(self.tmpdir, "prompts.db"))
+        self.addCleanup(self.api.db.close_all)  # runs before the rmtree cleanup
         orig_dirs = list(GalleryConfig.MONITORING_DIRECTORIES)
         self.addCleanup(setattr, GalleryConfig, "MONITORING_DIRECTORIES", orig_dirs)
 
diff --git a/tests/test_diagnostics_config.py b/tests/test_diagnostics_config.py
index c05b95b..9ecf077 100644
--- a/tests/test_diagnostics_config.py
+++ b/tests/test_diagnostics_config.py
@@ -185,7 +185,7 @@ class TestAdminEndpointsUseConfigPath(unittest.TestCase):
             self.assertGreater(len(result.body), 0)
             self.assertTrue(result.body.startswith(b"SQLite format 3\x00"))
         finally:
-            real_db.close()
+            real_db.close_all()
             for suffix in ("", "-wal", "-shm"):
                 if os.path.exists(db_file + suffix):
                     os.unlink(db_file + suffix)
diff --git a/tests/test_image_linking.py b/tests/test_image_linking.py
index 4f6714f..f75d18c 100644
--- a/tests/test_image_linking.py
+++ b/tests/test_image_linking.py
@@ -51,6 +51,7 @@ class LinkingTestCase(unittest.TestCase):
         )
 
     def tearDown(self):
+        self.db.close_all()  # Windows cannot unlink an open database file
         for path in (
             self.image,
             self.db_path,
diff --git a/tests/test_node_execution_contract.py b/tests/test_node_execution_contract.py
index 3889f2e..75de204 100644
--- a/tests/test_node_execution_contract.py
+++ b/tests/test_node_execution_contract.py
@@ -182,6 +182,7 @@ class NodeTestCase(unittest.TestCase):
         self.node.comfyui_integration = mock.Mock()
 
     def tearDown(self):
+        self.db.close_all()  # Windows cannot unlink an open database file
         for suffix in ("", "-wal", "-shm"):
             if os.path.exists(self.db_path + suffix):
                 os.unlink(self.db_path + suffix)
diff --git a/tests/test_utils_diagnostics.py b/tests/test_utils_diagnostics.py
index 64eef6f..33353d8 100644
--- a/tests/test_utils_diagnostics.py
+++ b/tests/test_utils_diagnostics.py
@@ -25,20 +25,23 @@ def same_path(a, b):
 
 class DiagnosticsTestCase(unittest.TestCase):
     def setUp(self):
-        self.tmp = tempfile.TemporaryDirectory()
+        self.tmp = tempfile.TemporaryDirectory(ignore_cleanup_errors=True)
         self.addCleanup(self.tmp.cleanup)
         self.db_path = os.path.join(self.tmp.name, "prompts.db")
         self.diag = GalleryDiagnostics(self.db_path)
 
     def _populate(self):
         db = PromptDatabase(self.db_path)
-        prompt_id = db.save_prompt(
-            text="a cat", prompt_hash=generate_prompt_hash("a cat")
-        )
-        image = os.path.join(self.tmp.name, "cat.png")
-        with open(image, "wb") as f:
-            f.write(b"x")
-        db.link_image_to_prompt(prompt_id=prompt_id, image_path=image, metadata={})
+        try:
+            prompt_id = db.save_prompt(
+                text="a cat", prompt_hash=generate_prompt_hash("a cat")
+            )
+            image = os.path.join(self.tmp.name, "cat.png")
+            with open(image, "wb") as f:
+                f.write(b"x")
+            db.link_image_to_prompt(prompt_id=prompt_id, image_path=image, metadata={})
+        finally:
+            db.close_all()  # Windows cannot delete the temp dir while it is open
         return prompt_id
 
     def _chdir(self, path):