Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/5930af4e7d5a1a684bd0e59694cf62e5.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563