Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d9d6b4b240fcfc20ba5a5e4ac2863407.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563