Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1d8fb1cb315f89f59a2d26082c5a3b56.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563