Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/ead56f0cae384b7c503c0466f63c2a0d.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563