The homepage, forum and wiki will be going offline for about five minutes on 2019-06-15, between 09:00 and 09:15 UTC.
In your local time (if you are logged in and have your time offset correctly configured), this is:
June 15, 2019, 09:00:00 AM
The intent is to install security updates on the server which hosts the homepage, forum and wiki. These will be non-disruptive to functionality, as the server is running a stable OS release that gets critical fixes only.