php - file not found when using header() in php7 -

when update php5.6 php7.0.2 i`m getting error 'file not found'. in php5.6 works fine, php.ini , other server settings same. code:

header('content-type: application/vnd.ms-excel'); header('content-disposition: attachment;filename="'.$this->name.'.xls"');// header('cache-control: max-age=0'); $objwriter->save('php://output'); 

while debug error appear after first , second line. server apache/2.4.18 (ubuntu).