From 62dd22d90d780c6c9f71af80aa1c8fc5f2498a53 Mon Sep 17 00:00:00 2001
From: Namira-Kamal <102487879+Namira-Kamal@users.noreply.github.com>
Date: Mon, 4 Dec 2023 09:01:39 -0500
Subject: [PATCH] Update apply.py assertion message

Improved assertion message for possible duplicate column names
---
 pandas/core/apply.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/apply.py b/pandas/core/apply.py
index bb3cc3a03760f..0c1a39b82aee8 100644
--- a/pandas/core/apply.py
+++ b/pandas/core/apply.py
@@ -651,7 +651,7 @@ def normalize_dictlike_arg(
             and any(is_list_like(v) for _, v in func.items())
         ) or (any(is_dict_like(v) for _, v in func.items())):
             # GH 15931 - deprecation of renaming keys
-            raise SpecificationError("nested renamer is not supported")
+            raise SpecificationError("nested renamer is not supported. Possible duplicate column names.")
 
         if obj.ndim != 1:
             # Check for missing columns on a frame