fallback to regular udf

python/pyspark/sql/connect/udf.py

@@ -86,6 +86,7 @@ def _create_py_udf(
                 "Arrow optimization for Python UDFs cannot be enabled.",
                 UserWarning,
             )
+            return regular_udf
     else:
         return regular_udf
 

python/pyspark/sql/udf.py

@@ -148,6 +148,7 @@ def _create_py_udf(
                 "Arrow optimization for Python UDFs cannot be enabled.",
                 UserWarning,
             )
+            return regular_udf
     else:
         return regular_udf