I have now done one full round of testing and everything seems to work fine. So the next steps are:

• I am now upgrading all the “mint” worlds that we use to reset lots. This will take most of today.
• I will then stop the server (watch for a blog post) and backup all worlds to my PC at home nad upgrade them as well to 1.16.2. Copying all worlds (including the huge darklands) to my PC and then upgrading it there and copying it back is faster then doing it on the server directly.
• Along with this process, I will do a check that all our plugins are up to the latest version.
• Then I will copy all the worlds back to the server and we will try to launch the server with 1.16.2

One option that we have is to instead of shutting the server down for a longer time (likely a whole day or more) is to upgrade world-by-world. This would mean that the server is online most of the time but only with the worlds that are already upgraded. I would start with the server having city, empire and nether online, the rest would then come in as they are upgraded. I prefer this solution as it would take some of the pressure away to get everything done as soon as possible. Specially the huge darklands would take a long time and if we don’t have to wait for this it would be better for everyone.

If the server is online without some worlds it would mean that users who logged off in those worlds would revert to the city spawn. Portals and warps to those worlds would simply fail. There should be no risk of stuff getting lost.

What do you think? Let me know in the comments.