Copy
Configs, plugins and your world (fresh flat world if it is over 3 GB) into a temporary folder.
For Paper server admins
Know what breaks
before you update.
Preflight starts a temporary copy of your server twice: as it is, then updated to the new Minecraft version with the new plugin releases. You get a report of what breaks, what was already broken and what the update fixes. Then the copy is deleted.
$
cobblekit preflight /path/to/server --to 26.3
One file, nothing to install. Java is found on your machine, or a temporary one is downloaded and removed.
Reference start
The copy starts as it is today, so old problems are not blamed on the update.
Update
New Paper build, new plugin releases from Modrinth and Hangar, your configs carried over with Cobblekit Merge.
Updated start
Started on a free local port, then stopped cleanly. A probe checks which plugins are really enabled.
Report, then cleanup
REPORT.md, report.json and both logs. The temporary copy is deleted.
Tested, not promised
A real update, measured
What Preflight reported (with plugin updates)
The same server, updating only Paper
Compared with the usual ways
| Cobblekit Preflight | Plugin updatersServerPatch, PluginPulse… | Manual test serverwhat hosting guides advise | Update and hope | |
|---|---|---|---|---|
| Finds plugin updates | yes | yes | by hand | by hand |
| Starts the updated server before you do | yes, isolated copy | no | yes | on your real server |
| Separates new problems from old ones | yes, reference start | no | if you test twice | no |
| Carries your configs over | yes (Merge) | no | by hand | plugin defaults |
| Leaves your server untouched | yes | stages new jars | yes | no |
| Your time | one command | one command | copy, download, start, read logs | until something breaks |
The other columns describe what those tools and methods do according to their own pages and the hosting guides; they were not run in this benchmark.
What it cannot do
- It does not play the game: a plugin that starts fine but misbehaves in play is not caught.
- Premium plugins and custom builds cannot be downloaded: they are tested as they are, and listed.
- A plugin whose author forgot to tag the new Minecraft version is tried with its latest release and flagged.
- Worlds over 3 GB are replaced by a fresh flat world unless you pass
--world copy; world conversion is then not tested. - It needs free disk space for one copy of your server, and some RAM (about the size of your server's own).
How the numbers were made
Is it safe to run next to my live server?
The copy listens on 127.0.0.1 with free ports, RCON and query disabled, at low CPU priority. Your server folder is only read. Make sure you have enough free RAM for one more server.
What does the probe do?
A 3 KB plugin is added to the temporary copy only. One second after the server is ready it writes which plugins are enabled, so the result does not depend on how each plugin words its log messages.
I compiled a plugin myself. Will it be replaced?
No. A jar that is not the exact file published on Modrinth or Hangar is kept as it is, because the public release may be older than your build. Use --update-unknown if you really want it replaced.