A KeyError in pandas usually happens when you try to access a column, row, or index label that doesn’t exist in your DataFrame. Here are some common reasons and solutions:

Typo or Mismatch: Double-check that the name you’re using to access the column/index is correct, including capitalization and any special characters.

Column Not Loaded: If you’re loading data from a CSV or another file, make sure the column actually exists. Sometimes data formats or headers can cause issues.

Chained Operations: When you use chained indexing like df[df["Column"] > 5]["NonexistentColumn"], pandas might lose track of the columns, leading to a KeyError. Try breaking it down or use .loc instead.

Column Dropped or Renamed: If you previously dropped or renamed a column, you won’t be able to access it with the old name. Verify with df.columns to see the current column names.