Msgstr "The specified package is invalid. Body is missing." In closed XML

I am using private XML to create an excel template. After filling in the data in the created excel, I am trying to import Excel with the data. It returns the error "The specified package is not valid. The main part is missing.", I am using an XLSX file.

try
 {
      var   workbook = new XLWorkbook(FILE_PATH);
}
catch (Exception ex)
{   
         throw;
}

      

        
        
        
      

    

It throws error when creating XLWOrkbook object using generated excel template.

Please provide a solution,

Thanks in Advance ...