Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/f10b3e3b78fa8e768d66e68e3c832557.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563