Cannot modify header information – headers already sent

Your plugin has a problem and should be updated:

Cannot modify header information – headers already sent in /public_html/wp-content/plugins/cbxuseronline/includes/class-cbxuseronline-helper.php on line 106

in that file:
setcookie( CBX_USERONLINE_COOKIE_NAME, $cookie_value, CB_RATINGSYSTEM_COOKIE_EXPIRATION_30DAYS, SITECOOKIEPATH, COOKIE_DOMAIN );