Pandas ValueError: Excel File Format Error - How to Fix

This error occurs when pandas is unable to determine the file format of the Excel file. To resolve this error, you need to specify the engine manually.

You can do this by adding the 'engine' parameter to the 'read_excel()' method and setting it to either 'openpyxl' or 'xlrd', depending on the version of Excel file you are using. For example:

import pandas as pd

# reading an Excel file with openpyxl engine
df = pd.read_excel('file.xlsx', engine='openpyxl')

# reading an Excel file with xlrd engine
df = pd.read_excel('file.xls', engine='xlrd')

Note that if you are using an older version of pandas, you may need to install the 'xlrd' package separately.