Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c8e22291d7a1ead9b9bd4d023de8ae93.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563