Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c06b2d5745a4db196a293f3e6c58d72c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563