ArcGIS Online is under maintenance:

[AbdoAbdelrasoul]

If a lot of citizens/public use ArcGIS Online to get info, it would
be nice to let them know ArcGIS online maps/services are not available due to
upgrading/maintenance (when you upgrade GIS Server, webadaptor, databases).

[ChristopherSchreiber]

If I understand your point correctly, you can use ArcGIS Online Health Dashboard  to view ArcGIS Online status. 

Chris

[AaronCohen]

Chris

You are misunderstanding.  

The point of this Idea is to tell the public who use the maps and apps in your AGOL site that the site is under maintenance. This is a very common practice so users don't try to use web pages that are being worked on.

In my case, we serve up all of our map services from our servers. We do not use hosted services. So when I am working on either the database server or map server, my AGOL sites that consume that data will not work correctly.

The Dashboard link you  provided is to tell YOU, the admin,  the health of ESRI's backend services.

Does that make sense now?

My work around was to temporarily insert text into my AGOL home page and Open Data site homepage that notified the user the site would be under maintenance for a short time on a given date/time.

Not very effective but its all I can do.

Aaron