Im Receiving this Error After i Sign up a New Account

Hi I Have Successfully Sign up a New Account But after that i see it on the Page when the user has verified their account , it is throwing a message like this,

Warning: Creating default object from empty value in /home/rfnet/public_html/wp-includes/ms-settings.php on line 111

Warning: Cannot modify header information – headers already sent by (output started at /home/rfnet/public_html/wp-includes/ms-settings.php:111) in /home/rfnet/public_html/wp-content/plugins/sitewide-privacy-options/sitewide-privacy-options.php on line 560

Here is my settings :

Theme is WordPress 2013

Plugins Installed:

Akismet

Anti-Splog

Domain Mapping plugin

Hello Dolly

Multisite Privacy

Password Protect Selected Content

Select Language At Signup

Status

WPMU DEV Dashboard

Please advice how to remove that notice,

My Debug mode is False , so it shouldnt have that error showing after a new user activated a new account