I received this notice from Social Strata:
We will be performing maintenance to update the software that powers your community. You can read about the software release in this blog post: link to Forum Refresh Release.
This maintenance is scheduled for May 13th, 2019. The maintenance window will be from 11:00 AM to 1:00 PM Eastern Daylight Time. During the maintenance window, there will be an outage of up to 1 hour.
The Social Strata Operations Team