Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/3b3be9272d2a283dd5a25a4b686a2b5e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563