Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/3f0354052d60ed4b4f0d29a488971a96.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563