Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/7fae0a5ba619a2ac67da3c6c12b1d3de.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563