diff --git a/src/aiida/orm/nodes/data/array/xy.py b/src/aiida/orm/nodes/data/array/xy.py
index 5171b1bc05..ed8ab64635 100644
--- a/src/aiida/orm/nodes/data/array/xy.py
+++ b/src/aiida/orm/nodes/data/array/xy.py
@@ -187,6 +187,8 @@ def get_y_arraynames(self) -> list[str]:
         """Returns the user-provided names of the y-arrays."""
 
         try:
-            return self.base.attributes.get('y_names')
+            y_names = self.base.attributes.get('y_names')
+            if y_names is None:
+                raise KeyError
         except (KeyError, AttributeError):
-            raise NotExistent(f'No y names been set yet')
\ No newline at end of file
+            raise NotExistent(f'No y names been set yet!')
\ No newline at end of file