Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c01c7b1e08e8af47225a3c6c446a158c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563