A few people have mentioned achieving long uptime. What is often overlooked is that it is possible for uptime to be too long.

It is quite possible for updates to not break a running system but make it so that it will break on the next reboot. E.g., a dynamic library gets updated in a way that breaks a server process. It doesn't affect the running server because it still has the old library loaded.

Next time you boot your server process doesn't start.

These kind of problems can be annoying to deal with, especially when your system has an uptime of years and for all you know whatever change broke it could have been in any one of dozens of updates you've applied over that time.