Abort mid-game

Hello, I just played a game where my opponent aborted mid-game. Captures had been made on pieces and pawns from both sides. I didn't know that someone can opt to abort in such a case. Is it so? If so, are there any conditions? Thank you!

If the game was aborted mid-game it could be either of these two things~

1. You were playing an Arena game, and the Arena ended. 

2. The server restarted. 

I can see a bunch of threads on games aborting right now, so I believe it must have been a scheduled server restart.

Thanks for the reply. It was definitely the second case. I saw the pop-up saying that the server is going to restart, but I wasn't aware of the consequence. Now I know. Thanks again.