Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/11a821ff08d3f9b56f652ec8c7b04727.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563