Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/41ea41f0ab8c56f9dc8df2319b1d5b96.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563