Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/405c84643b8f3c9b6c212f7fc63275da.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563