PHP - Error al imprimir el reporte de excel

Buenas noche el siguiente codigo me genera error asi:
Fatal error: Array and string offset access syntax with curly braces is no longer supported in C:\xampp\htdocs\FORMATO\Classes\PHPExcel\Shared\String.php on line 526

que puedo hacer para solucionar eso.

codigo :

<?php


// Incluir la libreria PHPExcel
require_once 'Classes/PHPExcel.php';

// Crea un nuevo objeto PHPExcel
$objPHPExcel = new PHPExcel();

// Establecer propiedades
$objPHPExcel->getProperties()
->setCreator("Francisco Gutierrez")
->setLastModifiedBy("Foxconn")
->setTitle("Cartas de Instruccion")
->setSubject("Cartas de Instruccion")
->setDescription("Cartas para Exportacion de Material Electrinico")
->setKeywords("Excel Office 2007 openxml")
->setCategory("Pruebas de Excel");

//formato de color a las fuentes "letras"
$objPHPExcel->getActiveSheet()->setShowGridlines(false);
$objPHPExcel-> getActiveSheet()->getStyle ('F2')->getFont ()-> getColor() -> setARGB (PHPExcel_Style_Color :: COLOR_BLUE);
$objPHPExcel-> getActiveSheet()->getStyle ('D3')->getFont ()-> getColor() -> setARGB (PHPExcel_Style_Color :: COLOR_BLUE);
$objPHPExcel-> getActiveSheet()->getStyle ('F4')->getFont ()-> getColor() -> setARGB (PHPExcel_Style_Color :: COLOR_BLUE);
$objPHPExcel-> getActiveSheet()->getStyle ('M9')->getFont ()-> getColor() -> setARGB (PHPExcel_Style_Color :: COLOR_RED);


// aliniamiento al contenido de las celdas
$objPHPExcel-> getActiveSheet()->getStyle('A5')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_LEFT);
$objPHPExcel-> getActiveSheet()->getStyle('A6:A12')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_RIGHT);
$objPHPExcel-> getActiveSheet()->getStyle('D6:D12')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_RIGHT);
$objPHPExcel-> getActiveSheet()->getStyle('L6:L12')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_RIGHT);
$objPHPExcel-> getActiveSheet()->getStyle('K48:K50')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_RIGHT);
$objPHPExcel-> getActiveSheet()->getStyle('K54:K57')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_RIGHT);
$objPHPExcel-> getActiveSheet()->getStyle('F2')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('D3')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('F4')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('D14')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('A15:O45')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('L56')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('L67')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('G57')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('G60:G66')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);
$objPHPExcel-> getActiveSheet()->getStyle('K44')->getAlignment()->setHorizontal(PHPExcel_Style_Alignment :: HORIZONTAL_CENTER);


//colocando los estilos de bordes
//bordes de todo el cuadro
$estilo = array(
'borders' => array(
'outline' => array(
'style' => PHPExcel_Style_Border:: BORDER_THIN
)
)
);
//borde bajo
$bordeBajo = array(
'borders' => array(
'bottom' => array(
'style' => PHPExcel_Style_Border:: BORDER_THIN
)
)
);
//rangos de los bordes
$objPHPExcel->getActiveSheet()->getStyle('A6:N12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A6:c12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('K6:N12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A6:A12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A6:N6')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('k6:L12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('D6:D12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A7:d7')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A8:C8')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A9:c9')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A10:c10')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A11:c11')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('d12:j12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('k8:n8')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('k10:n10')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('k12:n12')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A15:O15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('B15:C15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('F15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('I15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('K15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('M15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('O15')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A47:E57')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A48:E48')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A50:E50')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A52:C52')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A53')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('B53:E53')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A55:B55')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('C55:E55')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A57:E57')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('K47:M50')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('K48:M48')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('K50:M50')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('L54:L56')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('L55')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('L47:M47')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('L57:M57')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A51:E51')->applyFromArray($estilo);
$objPHPExcel->getActiveSheet()->getStyle('A45:O45')->applyFromArray($bordeBajo);
$objPHPExcel->getActiveSheet()->getStyle('G65:I65')->applyFromArray($bordeBajo);

//color en fondo de celdas
function cellColor($cells,$color){
global $objPHPExcel;
$objPHPExcel->getActiveSheet()->getStyle($cells)->getFill()->applyFromArray(array(
'type' => PHPExcel_Style_Fill::FILL_SOLID,
'startcolor' => array(
'rgb' => $color
)
));
}
cellColor('A47:E47', 'b4b5b7');
cellColor('A51:E51', 'b4b5b7');
cellColor('A55:E55', 'b4b5b7');
cellColor('K47:M47', 'b4b5b7');

//accion para poner en negritas
$objPHPExcel->getActiveSheet()->getStyle('F2')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('D3')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('A6:A12')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('D6:D12')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('K6:L12')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('A14:O15')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('G16:H27')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('A47')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('D48')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('A51')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('A55')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('K47:M47')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('A59:A62')->getFont()->setBold(true);
$objPHPExcel->getActiveSheet()->getStyle('G16')->getFont()->setBold(true);

//cambio de tamaño de letra y tipografia
$font1 = array(
'font' => array(
'size' => 12,
'name' => 'Arial'
));
$objPHPExcel->getActiveSheet()->getStyle('F2')->applyFromArray($font1);
$objPHPExcel->getActiveSheet()->getStyle('A14:N14')->applyFromArray($font1);
$font2 = array(
'font' => array(
'size' => 16,
'name' => 'Arial'
));
$objPHPExcel->getActiveSheet()->getStyle('D3')->applyFromArray($font2);
$font3 = array(
'font' => array(
'size' => 7,
'name' => 'Arial'
));
$objPHPExcel->getActiveSheet()->getStyle('F4')->applyFromArray($font3);
$objPHPExcel->getActiveSheet()->getStyle('A5:N5')->applyFromArray($font3);
$objPHPExcel->getActiveSheet()->getStyle('A59:A66')->applyFromArray($font3);

$font4 = array(
'font' => array(
'size' => 10,
'name' => 'Arial'
));
$objPHPExcel->getActiveSheet()->getStyle('A15:O57')->applyFromArray($font4);
$font5 = array(
'font' => array(
'size' => 8,
'name' => 'Arial'
));
$objPHPExcel->getActiveSheet()->getStyle('A6:N12')->applyFromArray($font5);

//Agrega imagenes al archivo excel
$objDrawing = new PHPExcel_Worksheet_Drawing();
$objDrawing->setName('imgLogo');
$objDrawing->setDescription('LOGO');
$img = 'imagenes/fox.png'; //url para importar la imagen
$objDrawing->setPath($img);
$objDrawing->setOffsetX(28);
$objDrawing->setOffsetY(300);
$objDrawing->setCoordinates('A1'); // celda donde se va a posicionar
$objDrawing->setHeight(50); // tamaño del logo en pixeles
$objDrawing->setWorksheet($objPHPExcel->setActiveSheetIndex());

//Establece el rango de impresion en columnas
$objPHPExcel->getActiveSheet()->getPageSetup()->setPrintArea('A1:O67');

//Establece el rango de impresion con %
$objPHPExcel->getActiveSheet()->getPageSetup()->setFitToPage(false);
$objPHPExcel->getActiveSheet()->getPageSetup()->setScale(60);

//Establece el rango de impresion acomodando margen
$objPHPExcel->getActiveSheet()->getPageMargins()->setTop(0.20);
$objPHPExcel->getActiveSheet()->getPageMargins()->setLeft(0.25);
$objPHPExcel->getActiveSheet()->getPageMargins()->setHeader(0.20);
$objPHPExcel->getActiveSheet()->getPageMargins()->setRight(0.25);
$objPHPExcel->getActiveSheet()->getPageMargins()->setBottom(0.09);
$objPHPExcel->getActiveSheet()->getPageMargins()->setFooter(0.09);

//formato a celdas en ancho y alto
$objPHPExcel->getActiveSheet()->getColumnDimension('A')->setWidth(13.57);
$objPHPExcel->getActiveSheet()->getColumnDimension('B')->setWidth(13.57);
$objPHPExcel->getActiveSheet()->getColumnDimension('C')->setWidth(2.14);
$objPHPExcel->getActiveSheet()->getColumnDimension('D')->setWidth(9.00);
$objPHPExcel->getActiveSheet()->getColumnDimension('E')->setWidth(17.43);
$objPHPExcel->getActiveSheet()->getColumnDimension('F')->setWidth(15.14);
$objPHPExcel->getActiveSheet()->getColumnDimension('G')->setWidth(16.71);
$objPHPExcel->getActiveSheet()->getColumnDimension('H')->setWidth(17.29);
$objPHPExcel->getActiveSheet()->getColumnDimension('I')->setWidth(8.86);
$objPHPExcel->getActiveSheet()->getColumnDimension('J')->setWidth(10.71);
$objPHPExcel->getActiveSheet()->getColumnDimension('K')->setWidth(11.43);
$objPHPExcel->getActiveSheet()->getColumnDimension('L')->setWidth(11.86);
$objPHPExcel->getActiveSheet()->getColumnDimension('M')->setWidth(17.14);
$objPHPExcel->getActiveSheet()->getColumnDimension('N')->setWidth(15.43);
$objPHPExcel->getActiveSheet()->getColumnDimension('O')->setWidth(19.00);
$objPHPExcel->getActiveSheet()->getColumnDimension('P')->setWidth(2.86);
$objPHPExcel->getActiveSheet()->getRowDimension('2')->setRowHeight(13.50);
$objPHPExcel->getActiveSheet()->getRowDimension('3')->setRowHeight(18.00);
$objPHPExcel->getActiveSheet()->getRowDimension('4')->setRowHeight(11.25);
$objPHPExcel->getActiveSheet()->getRowDimension('5')->setRowHeight(15.75);

//combina celdas agrupando de una a varias
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('F2:I2');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('D3:L3');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('F4:I4');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('D14:L14');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('D15:E15');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('G15:H15');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('D16:E16');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('D19:E19');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('G16:H16');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('G19:H19');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('G60:I60');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('G66:I66');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('L57:M57');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('K47:M47');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('K48:L48');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('K49:L49');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells('K50:L50');



$fechaF=$_POST['fechaF'];

// Agregar Informacion en las celdas
$objPHPExcel->setActiveSheetIndex(0)
->setCellValue('F2', 'PROYECTO DIRECT SHIP')
->setCellValue('D3', 'PCE PARAGON SOLUTIONS (MEXICO) S.A. DE C.V.')
->setCellValue('F4', 'Camino al Castillo No.2100 M El Salto, Jalisco 45680')
->setCellValue('A5', 'Datos Agente Aduanal:')
->setCellValue('D5', 'Destino:')
->setCellValue('A6', 'Fecha Factura:')
->setCellValue('A7', 'Para:')
->setCellValue('A8', 'Compania:')
->setCellValue('A9', 'TEL:')
->setCellValue('A10', 'Contacto')
->setCellValue('A11', 'CIA:')
->setCellValue('A12', 'TEL:')
->setCellValue('B7', 'Elizabeth Montiel')
->setCellValue('B8', 'Adualink')
->setCellValue('B10', 'Analista de Dist.')
->setCellValue('B11', 'PCE PARAGON')
->setCellValue('B12', '3284 4100 ext.')
->setCellValue('D6', 'Compañía:')
->setCellValue('D7', 'Direccion:')
->setCellValue('D12', 'Tax ID:')
->setCellValue('E12', 'N/A')
->setCellValue('L6', 'AWB:')
->setCellValue('L7', 'Incoterm:')
->setCellValue('L8', 'Carrier :')
->setCellValue('L9', 'Seguro:')
->setCellValue('L10', 'Flete / Gastos:')
->setCellValue('L11', 'Cuenta:')
->setCellValue('L12', 'Nivel de servicio:')
->setCellValue('M7', 'DDP')
->setCellValue('M9', 'Favor de asegurar este embarque')
->setCellValue('M10', 'PREPAID')
->setCellValue('G16', 'UNIDAD DE PROCESAMIENTO DIGITAL')
->setCellValue('D14', 'CARTA DE INSTRUCCIONES PARA AGENTE ADUANAL')
->setCellValue('A15', 'Factura')
->setCellValue('B15', 'Orden')
->setCellValue('D15', 'Descripcion')
->setCellValue('F15', '#Parte')
->setCellValue('G15', 'Des_Espanol')
->setCellValue('I15', 'Cantidad')
->setCellValue('J15', 'Precio_unit')
->setCellValue('K15', 'V. Factura')
->setCellValue('L15', 'Fraccion')
->setCellValue('M15', 'Valor Agregado')
->setCellValue('N15', 'Costo NO NAFTA')
->setCellValue('O16', 'PT')
->setCellValue('O19', 'EB')
->setCellValue('H25', 'TOTALES')
->setCellValue('I25', '=SUM(I16:I19)')
->setCellValue('K25', '=(J16)')
->setCellValue('O15', 'Identificador partida')
->setCellValue('A47', 'INFORMACION DEL PEDIMENTO')
->setCellValue('A48', 'PEDIMENTO PARA SERVERS:')
->setCellValue('D48', 'RT PT')
->setCellValue('A51', 'IDENTIFICADORES')
->setCellValue('A52', 'NIVEL DE PEDIMENTO: ')
->setCellValue('B52', 'ST 99')
->setCellValue('D52', 'A NIVEL PARTIDA:')
->setCellValue('A53', 'IM')
->setCellValue('B53', 'IC')
->setCellValue('A55', 'REGISTROS O PROGRAMAS')
->setCellValue('A56', 'No de Programa IMMEX: 187-2008')
->setCellValue('K47', 'DATOS DEL EMBARQUE:')
->setCellValue('K48', 'NUMERO DE CAJA:')
->setCellValue('K49', 'SELLO ADUANAL:')
->setCellValue('K50', 'SELLO PAPEL:')
->setCellValue('K54', 'PESO NETO:')
->setCellValue('K55', 'PESO BRUTO:')
->setCellValue('K56', 'BULTOS:')
->setCellValue('K57', 'MEDIDAS:')
->setCellValue('L56', '1')
->setCellValue('L57', 'VER DETALLE EN FACTURA')
->setCellValue('G60', 'ATENTAMENTE')
->setCellValue('G66', 'ANALISTA DE EXPORTACION')
->setCellValue('A59', 'DECLARAR EL DESTINATARIO DE CADA UNA DE LAS FACTURAS EN EL BLOQUE ')
->setCellValue('A60', 'QUE LE CORRESPONDE AL PEDIMENTO, DE ACUERDO AL INSTRUCTIVO DE LLENADO ')
->setCellValue('A61', 'ANEXO 22 RMCE  "Datos del Destinatario".')
->setCellValue('A62', 'Declarar esta leyenda en el campo de observaciones del pedimento')
->setCellValue('A63', 'Se anexa factura comercial')
->setCellValue('A64', 'No se paga el D.T.A de conformidad con el Art. 49 segundo parrafo, de la Ley Federal de Derechos.')
->setCellValue('A65', 'PCE PARAGON SOLUTIONS DE MEXICO S.A. DE C.V. Camino al Castillo No.2100 Edificio 7-A ')
->setCellValue('A66', 'Corredor Industrial El Salto, Jalisco C.P. 45680 ')

->setCellValue('B6',$fechaF);
//->setCellValue('E7',$facturaIn['$facturaIn'])
//->setCellValue('M6',$direccion=$_POST['direccion'])
//->setCellValue('M8',$AWB=$_POST['AWB'])
//->setCellValue('A16',$carrier=$_POST['carrier'])
//->setCellValue('B16', $descripcion=$_POST['descripcion'])
//->setCellValue('D16',$parte=$_POST['parte'])
//->setCellValue('F16',$cantidad=$_POST['cantidad'])
//->setCellValue('I16',$precio=$_POST['precio'])
//->setCellValue('J16',$vfact=$_POST['vfact'])
//->setCellValue('K16',$peso=$_POST['peso'])
//->setCellValue('L54',$nivel=$_POST['nivel'].'Kg')
//->setCellValue('L12',$compaDes=$_POST['compaDes'])
//->setCellValue('E6',$aduana=$_POST['aduana'])
//->setCellValue('B8',$compTrans=$_POST['compTrans'])
//->setCellValue('B7',$dscrip=$_POST['dscrip']);

// Renombrar Hoja
$objPHPExcel->getActiveSheet()->setTitle('Cartas de Instruccion');

// Establecer la hoja activa, para que cuando se abra el documento se muestre primero.
$objPHPExcel->setActiveSheetIndex(0);

// Se modifican los encabezados del HTTP para indicar que se envia un archivo de Excel.
header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="cartas.xlsx"');
header('Cache-Control: max-age=0');
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->save('php://output');
exit;
?>

Hola,

el mismo error te da la pista:

Fatal error: Array and string offset access syntax with curly braces is no longer supported in C:\xampp\htdocs\FORMATO\Classes\PHPExcel\Shared\String.php on line 526

Error grave: la sintaxis de acceso de desplazamiento de matriz y cadena con llaves ya no se admite en C:\xampp\htdocs\FORMATO\Classes\PHPExcel\Shared\String.php en la línea 526

Busca en la linea 256 del archivo C:\xampp\htdocs\FORMATO\Classes\PHPExcel\Shared\String.php y seguramente tendrás un índice encerrado entre llaves {} que posiblemente deba encerrarse entre corchetes [].

De todas formas, Googleando he visto que la librería que usas PHPExcel está abandonada, por lo que es posible que deje de funcionar definitivamente. En su lugar recomiendan usar PHPSpreadsheet

Un saludo!