Excel file format cannot be determined, you must specify an engine manually.

This error message usually occurs when you try to read an Excel file using Pandas and the file format cannot be automatically determined. To fix this, you need to manually specify the engine to use for reading the file.

You can do this by adding the "engine" parameter to the read_excel() function and setting it to the appropriate value. For example, if you have an Excel file named "data.xlsx" and you want to read it using the openpyxl engine, you can use the following code:

import pandas as pd
data = pd.read_excel('data.xlsx', engine='openpyxl')

Other possible values for the engine parameter include "xlrd" and "xlsxwriter", depending on the library you have installed and the file format you are using.