Why does my site display "This site is undergoing maintenance"?
Customer Portal (all versions)
If you are seeing this message after cutover, for your upgrade site, then this is due to this site is now disabled.
During the update process, your production site is copied to an upgrade site and updated to the designated software version. Prior to cutover, you can access this site but after "cutover", this site is disabled with site mode of "maintenance". The "undergoing maintenance" message you see appears for sites in maintenance mode.
For more information, refer to the following published answers: