Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/769e9fd9a4ddba5f6a4a150614a5e96c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563