Convert excel format exception.You can try specifying the 'excelType' yourself

This exception occurs when you are trying to read an Excel file using a library or tool that cannot determine the Excel file format automatically. To resolve this issue, you can try specifying the 'excelType' yourself.

Here's an example of how you can specify the 'excelType' when reading an Excel file using the Apache POI library in Java:

FileInputStream file = new FileInputStream(new File("example.xlsx"));

Workbook workbook = new XSSFWorkbook(file); // for .xlsx files
// or
Workbook workbook = new HSSFWorkbook(file); // for .xls files

Sheet sheet = workbook.getSheetAt(0);

// read the data from the sheet...

workbook.close();
file.close();

In the above code, you can replace the line `Workbook workbook = new XSSFWorkbook(file);` with `Workbook workbook = WorkbookFactory.create(file, ExcelType.XSSF);` if you know that the Excel file is in the `.xlsx` format. Similarly, you can replace it with `Workbook workbook = WorkbookFactory.create(file, ExcelType.HSSF);` if you know that the Excel file is in the `.xls` format.

Hope this helps!