KeyError in Pandas DataFrame

Why This Happens

Pandas raises KeyError when you access a column that does not exist. Column names are case-sensitive and may contain hidden whitespace from CSV parsing.

The Problem

import pandas as pd
df = pd.read_csv('data.csv')
print(df['Name'])  # KeyError if column has leading space

The Fix

import pandas as pd
df = pd.read_csv('data.csv')
df.columns = df.columns.str.strip()
print(df['Name'])

Step-by-Step Fix

1. 1

   List all columns

   Run print(df.columns.tolist()) to see exact column names.

2. 2

   Strip column names

   Clean up with df.columns = df.columns.str.strip().

3. 3

   Check case sensitivity

   'Name' and 'name' are different columns.