Direct answer
Update a Fabric server by matching the Minecraft game version, Fabric Loader and every mod/dependency as a tested set. Updating only one JAR can leave a valid Java process that still cannot load its mods.
Step-by-step procedure
- Stop the server and back up the world,
mods/,config/, loader files and the exact startup command. - Read the modpack’s release notes and compatibility matrix; prepare a separate instance with the intended Minecraft and Fabric Loader versions.
- Install the matching server-side loader and mod builds; remove duplicate old mod versions rather than leaving both JARs.
- Start staging, resolve the first mod dependency error, then test world load, player join and data persistence before switching production.
Common mistakes and trade-offs
A Minecraft world upgraded in a newer version is not guaranteed to open safely in an older game version. Do not revert by swapping the loader JAR alone.
How to verify it worked
Compare startup log versions and test a known modded recipe/block in a cloned world; confirm there are no missing registry entries.
Version and platform differences
Client-only mods do not normally belong on the dedicated server. Exact Java requirements depend on the Minecraft and modpack release.
Official references
These sources were checked for the current MSH revision. Version-sensitive details should always be confirmed against the project documentation for the release you run.
Related guides
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