Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/73786a7838e84c90f959d3876f63bea5.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563