Update safely

Different layers, different updates#

Fabric Loader, Minecraft, Java, Fabric API, individual mods, Crafty and ZimaOS are separate layers. Updating Minecraft is a compatibility migration; updating a mod within the same Minecraft version is usually smaller. A ZimaOS update changes the host, while a Crafty update changes the panel/container.

One calm update window#

1. 1
   Tell players when the server will be offline.
2. 2
   Stop the server normally and create a verified backup.
3. 3
   Save the current mod list and version numbers.
4. 4
   Read release notes for the one layer being changed.
5. 5
   Update Fabric Loader if the target mods require it.
6. 6
   For a Minecraft version change, select the required Java release.
7. 7
   Update Fabric API and mods to builds for the target Minecraft version.
8. 8
   Remove unsupported mods only after checking whether their saved data needs migration.
9. 9
   Start and read the complete log.
10. 10
    Test locally with the matching client profile before inviting players.

When the update fails#

Stop instead of repeatedly launching. Save the new log, compare its first error with the mod list, and either fix that named dependency or restore the full known-good backup. Never open a valuable world in an older Minecraft version after it has been saved by a newer one.