Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/0d95b0c7945cfc26e88b38df1fa41dd5.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563