Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/fe0cdb5bb6a5b87b0e6cf6877ba29b19.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563