diff --git a/edge-ai-platform/server/scripts/kneron_bridge.py b/edge-ai-platform/server/scripts/kneron_bridge.py
index 5638b1b..4526b0d 100644
--- a/edge-ai-platform/server/scripts/kneron_bridge.py
+++ b/edge-ai-platform/server/scripts/kneron_bridge.py
@@ -703,6 +703,10 @@ def handle_connect(params):
         last_err = None
         for attempt in range(max_retries):
             try:
+                # Clear any stale device group from previous failed attempt
+                # to prevent DeviceGroup.__del__ access violation during GC.
+                _device_group = None
+
                 if use_without_check:
                     _log(f"{_device_chip}: connect_devices_without_check(usb_port_id={target_dev.usb_port_id}, connectable={target_dev.is_connectable}) attempt {attempt+1}/{max_retries}...")
                     _device_group = kp.core.connect_devices_without_check(
@@ -717,6 +721,7 @@ def handle_connect(params):
                 last_err = None
                 break
             except Exception as conn_err:
+                _device_group = None  # prevent __del__ crash on stale handle
                 last_err = conn_err
                 _log(f"connect attempt {attempt+1} failed: {conn_err}")
                 if attempt < max_retries - 1:
@@ -738,7 +743,8 @@ def handle_connect(params):
         if last_err is not None:
             hint = ""
             if sys.platform == "win32":
-                hint = " On Windows, ensure the WinUSB driver is installed for this device (use Zadig: https://zadig.akeo.ie)."
+                hint = (" On Windows, ensure the WinUSB driver is installed for this device."
+                        " Re-run the installer or use Zadig (https://zadig.akeo.ie).")
             raise RuntimeError(f"Failed to connect after {max_retries} attempts: {last_err}.{hint}")
 
         # KL720 needs longer timeout for large NEF transfers (12MB+ over USB)