diff --git a/openwisp_controller/connection/base/models.py b/openwisp_controller/connection/base/models.py
index 441bfe73f..cb6d47523 100644
--- a/openwisp_controller/connection/base/models.py
+++ b/openwisp_controller/connection/base/models.py
@@ -367,7 +367,7 @@ def update_config(self):
                 self.connector_instance.update_config()
             except Exception as e:
                 logger.exception(e)
-            else:
+            finally:
                 self.disconnect()
 
     def save(self, *args, **kwargs):
diff --git a/openwisp_controller/connection/tasks.py b/openwisp_controller/connection/tasks.py
index 56e6a7bb1..1d7b3be07 100644
--- a/openwisp_controller/connection/tasks.py
+++ b/openwisp_controller/connection/tasks.py
@@ -20,13 +20,14 @@ def _is_update_in_progress(device_id, current_task_id=None):
     active = current_app.control.inspect().active()
     if not active:
         return False
+    device_id_str = str(device_id)
     # check if there's any other running task before adding it
     # exclude the current task by comparing task IDs
     for task_list in active.values():
         for task in task_list:
             if (
                 task["name"] == _TASK_NAME
-                and str(device_id) in task["args"]
+                and device_id_str in [str(arg) for arg in task.get("args", [])]
                 and task["id"] != current_task_id
             ):
                 return True