How to disable Multibyte function overloading in PHP for string functions - php

Question

I got a problem when call the PHPExcel library AutoLoader.php file.
I try to upload the Excel file, then after clicking on the upload button, it saves data into the database. I get an error, as shown in the photo after uploading the file. How can I fix this?
<?php
require('library/Classes/PHPExcel/IOFactory.php');
/** Include path **/
set_include_path(get_include_path() . PATH_SEPARATOR . '../Classes/');
if(isset($_POST['submit'])){
if((isset($_POST['file'])) && !empty($_POST['file']))
{
$file = $_POST['file'];
}
$fileName= $_FILES["file"]["name"];
echo ('fileName +'.$fileName);
//$uploadPath = $_SERVER['DOCUMENT_ROOT'].'/SMS/excel/' ;
$fileTempName= $_FILES["name"]["temp_name"];
//echo ('fileTempName +'.$fileTempName);
$fileExtension= pathinfo($fileName,PATHINFO_EXTENSION);
$allowedtype= array('xlsx','sls','xlsm');
if(!in_array($fileExtension,$allowedtype)){
echo("<br/>Sorry, File type is not allowed. Only Excel file.");
}
else {
echo("Correct File Extension");
try
{
$inputfiletype = PHPExcel_IOFactory::identify($fileName);
$objReader = PHPExcel_IOFactory::createReader($inputfiletype);
$objPHPExcel = $objReader->load($fileName);
echo 'Reading the number of Worksheets in the WorkBook<br />';
/** Use the PHPExcel object's getSheetCount() method to get a count of the number of WorkSheets in the WorkBook */
$sheetCount = $objPHPExcel->getSheetCount();
echo 'There ',(($sheetCount == 1) ? 'is' : 'are'),' ',$sheetCount,' WorkSheet',(($sheetCount == 1) ? '' : 's'),' in the WorkBook<br /><br />';
echo 'Reading the names of Worksheets in the WorkBook<br />';
/** Use the PHPExcel object's getSheetNames() method to get an array listing the names/titles of the WorkSheets in the WorkBook */
$sheetNames = $objPHPExcel->getSheetNames();
foreach($sheetNames as $sheetIndex => $sheetName) {
echo 'WorkSheet #',$sheetIndex,' is named "',$sheetName,'"<br />';
}
}
catch(Exception $e)
{
die('Error loading file "'.pathinfo($fileName,PATHINFO_BASENAME).'": '.$e->getMessage());
}
}
}
?>