Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/47412f335ecfd1f8e1f92fb7f332da7a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563