Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/9035a1797b6d6660a32c4c2e63b0f7a3.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563