Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/25fe3a1d495e38403d6d77a733781a93.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563