Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/9c4ef9b5da65c5a6ca9f18dad7d62178.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563