Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/bca7ca73f7a990729f467433f0c1b20a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563