Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/047aca3be0ad9e4b0de4e5cf1c840bb5.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563