Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1f10f736009e7d04969f5c5f06b2c355.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563