Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/622b826818eb63cd5f2c57f3bc10b3aa.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563