Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/63cf04a3e02c7b6cb9a537f35f258080.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563