diff --git a/algorithms/2_BubbleSort/bubble_sort_exercise_solution.py b/algorithms/2_BubbleSort/bubble_sort_exercise_solution.py
index df838f7..6e8c7f9 100644
--- a/algorithms/2_BubbleSort/bubble_sort_exercise_solution.py
+++ b/algorithms/2_BubbleSort/bubble_sort_exercise_solution.py
@@ -3,8 +3,15 @@ def bubble_sort(elements, key=None):
     size = len(elements)
 
     for i in range(size-1):
+        if key is None:
+            print("please enter a key to start search.")
+            break
         swapped = False
+        breakloop =False
         for j in range(size-1-i):
+            if key not in elements[j]:
+                breakloop = True
+                break
             a = elements[j][key]
             b = elements[j+1][key]
             if a > b:
@@ -12,6 +19,10 @@ def bubble_sort(elements, key=None):
                 elements[j] = elements[j+1]
                 elements[j+1] = tmp
                 swapped = True
+         
+         if breakloop:
+            print("key is not correct")
+            break
 
         if not swapped:
             break
@@ -25,4 +36,4 @@ def bubble_sort(elements, key=None):
     ]
 
     bubble_sort(elements, key='transaction_amount')
-    print(elements)
\ No newline at end of file
+    print(elements)