Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/949ed9be30c2f8a578b72e24c1f30ab9.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563