Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/ade1f32d49507201fbc85eb6981c7f2a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563