What is a server shutdown? When do they happen?
Every so often Chess.com needs to shut down the servers for maintenance. When the servers shut down, any live games (bullet, blitz, or rapid games, Daily games are NOT affected) that are being played will be declared aborted. These aborted games will not provide any rating change, and will not show in the game archive. They will not count as a win or loss, it will be as if they never happened.
To avoid this happening, server shutdowns are announced 40 minutes in advance by a banner at the bottom of the screen.
Server shutdowns are not regularly scheduled, and happen on an as needed bases, but they usually happen about once per week, between the hours of 1AM and 3AM Pacific Time, and typically last only a few minutes.
This means, if you were to see the banner, you'd only have to make sure you weren't in a game at the listed time, then wait a few minutes, and everything would be back up and running!
Server restarts help us keep the servers in top shape! If you see the announcement, simply avoid playing at the set time for the shutdown, and you have nothing to worry about!