Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/5f85b7db9d45b92f2b393edd207a7c71.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563