Server & Performance guides
Guides to running a Minecraft Java server: setup and the EULA, JVM flags, server.properties, the whitelist and op, and which settings affect performance.
How to make a Minecraft server: Java 25, the EULA and the whitelist
Setting up the official 26.3 Java server step by step: it needs Java 25, stops once for the EULA, and now ships with the whitelist switched on.
Aikar's flags change at 12 GB — five of them, and one goes down
Copying a 4 GB flag set onto a 16 GB server leaves five values wrong. Here is exactly which five, plus the player count where a modded server crosses the line and a vanilla one does not.
Whitelist, ban and op: the server commands that behave differently than you expect
Whitelisting does not kick players already online, /ban needs a reason to be useful, and op level matters more than the op list. The details that bite server owners.
server.properties: the settings that change performance, and the ones that do nothing
view-distance and simulation-distance are not the same lever, and one of them is where your TPS goes. What each setting actually costs, with sensible values.
server-icon.png: the exact requirements, and the management API nobody uses
64x64, PNG, at the server root — get any of the three wrong and the icon silently does not appear. Plus the JSON-RPC management API that replaced screen-scraping the console.