Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/243e1b371fe4f7c26a835f3f33fd1c7e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563