Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/a25b899c60eb035a63e6691fd6d82a17.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563