Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/825bd2ac0c7caaf0478305a8a0a2db98.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563