Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/e6c1b15db97bdf54f17aa20d9ae7ea07.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563