Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/0f7387f21e188378f2255c5395b8a60e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563