( ! ) Notice: Use of undefined constant PHPEXCEL_ROOT - assumed 'PHPEXCEL_ROOT' in C:\wamp64\www\bo\vendor\phpoffice\phpexcel\Classes\PHPExcel\Autoloader.php on line 70
Call Stack
#	Time	Memory	Function	Location
1	0.0578	247304	{main}( )	...\Autoloader.php:0
2	0.0578	248112	spl_autoload_call ( )	...\Autoloader.php:11
3	0.0578	248216	PHPExcel_Autoloader::load( )	...\Autoloader.php:11

( ! ) Fatal error: Class 'PHPExcel_Shared_String' not found in C:\wamp64\www\bo\vendor\phpoffice\phpexcel\Classes\PHPExcel\Autoloader.php on line 11
Call Stack
#	Time	Memory	Function	Location
1	0.0578	247304	{main}( )	...\Autoloader.php:0