Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/98deac74fcb61f4b37876d4cf9898e39.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563