Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/84e06afc0d9109798dbee16805d3c9b5.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563