Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/cbe3a337d9c8b28d755337a1c59da445.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563