Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d58c1ca6f3e667b32464ca7e722f7ca0.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563