Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/94d70a68e724d7aec58c11c37e70d4c9.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563