Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d4f7af1d98cea5c95fd2d873a92e0177.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563