diff --git a/python_app/scripts/laser_temp_monitor.py b/python_app/scripts/laser_temp_monitor.py
index b8a21e0..86a8d67 100644
--- a/python_app/scripts/laser_temp_monitor.py
+++ b/python_app/scripts/laser_temp_monitor.py
@@ -26,6 +26,7 @@ from python_app.hardware_full.laser_control.controller import (
     DEVICE_MAIN_MESSAGE_ID,
     LaserController,
 )
+from python_app.hardware_full.laser_control.exceptions import PortBusyError
 from python_app.hardware_full.laser_control.models import VariationType
 from python_app.hardware_full.laser_control.monitoring import (
     DEFAULT_READINGS_PATH,
@@ -114,7 +115,13 @@ def main() -> int:
         pi_coeff2_p=laser.pi_coeff2_p,
         pi_coeff2_i=laser.pi_coeff2_i,
     )
-    controller.connect()
+    try:
+        controller.connect()
+    except PortBusyError as exc:
+        # Expected, benign conflict: the manual-control UI (or another monitor)
+        # already owns the port. Exit cleanly with guidance, not a traceback.
+        logger.error("%s", exc)
+        return 2
     try:
         if args.start:
             _start_variation(controller, variation)