Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/bc160b14c30dcde0d1b1d269e165fd4a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563