cannot open file generated by PHPReport and PHPExcel - php

Question

I have used the PHPReport library content with the PHPExcel Library content. I am creating the website locally on my macbook using Xampp. The following code I wrote to fetch the data and generate the excel sheet:
public function fetchReportData($newStartDate, $newEndDate){
if ($this->getDBConnection()) {
$q = "select * from PMA where request_date between '".$newStartDate."' and '".$newEndDate ."'";
$r = mysqli_query($this->dbc, $q);
if ($r) {
$row_count = $r->num_rows;
if ($row_count == 0) {
echo '<div align="left">'
. '<b><font color="red">* </font>No requests were found in this period</b></div>';
} else {
$data = array();
while ($row = mysqli_fetch_array($r)) {
$desc = $this->returnDesc($row[0]);
$requestId = $this->getNormalReqID($row[0]);
$this->get($requestId);
$username = $this->getUserName($this->requestor_id);
$srv_id = $this->getSRVId($row[0]);
$this->getSRV($srv_id);
$srv_date = date("d-m-Y", strtotime($this->srv_date));
$srv = 'SRV dtd '.$srv_date;
if($this->srv_remarks == null)
{
$remark = $srv;
}
else
{
$remark = $this->srv_remarks;
}
$data[] =
array("Date" => $row[2], "Originator" => $username, "Material No" => $this->material_number,
"Description" => $desc, "Quantity" => $row[5], "Order Number" => $this->pm_order_number,
"Request Number" => $row[7], "Gate Pass No"=> $row[10], "Gate Pass Date"=> $row[14],
"SRV/Date" => $srv, "Received Qty" => $row[11], "Remarks" => $remark)
;
}
include_once 'PHPReport.php';
$R=new PHPReport();
$R->load(array(
'id'=>'product',
'header'=>array(
'Date'=>'Date', 'Originator' => 'Originator', 'Material No' => 'Material No',
'Description' => 'Description' , 'Quantity' => 'Quantity', 'Order Number' => 'Order Number',
'Request Number' => 'Request Number', 'Gate Pass No' => 'Gate Pass No', 'Gate Pass Date'=> 'Gate Pass Date',
'SRV/Date' => 'SRV/Date' , 'Received Qty' => 'Received Qty', 'Remarks' => 'Remarks'
),
'footer'=>array(
'Date'=>'', 'Originator' => '', 'Material No' => '',
'Description' => '' , 'Quantity' => '', 'Order Number' => '',
'Request Number' => '', 'Gate Pass No' => '', 'Gate Pass Date'=> '',
'SRV/Date' => '' , 'Received Qty' => '', 'Remarks' => ''
),
'data'=> $data
)
);
echo $R->render('excel');
}
}
}
}
It does not show any error while calling the code and it generates the xlsx sheet fine but I cannot open the file. I get the following error when I try to open the sheet:
The format or file extension is not valid. verify that the file has not been corrupted and the file extension matches the format of the file.
I get the same error while trying to open a PDF created by the library PHP to PDF, is it something wrong with my macbook?