Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d16a9326d7a60c54ad6538e68d1d232c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563