We plan to update the operating system running stendhalgame.org on Sunday, the 22th of June around noon server time. The update is expected to take less than two hours. During this time the Stendhal server will briefly unavailable.
Update: The server is back up. The game was down for about 10 minutes. Due to incompatibilities with the new Apache version, the website was offline for about an hour, and we had to disable spdy. So far everything else seems to work fine.