Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/5d1e016cc3593cd7f3a9dc6b19b86944.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563