Paper Plugin Guide
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Tools

Test Server

Start a real Paper 26.3 server with the guide's plugins and use its console from this page.

IntermediateTool

Start a real Paper 26.3 server on your own PC with the guide's example plugins or the jars you built in the Compile Lab, watch its console, type commands, and join it from Minecraft to see your plugins work.

Why test on a real server?

A plugin that compiles is not finished yet. Compiling only proves the Java is correct. To see whether your welcome message really shows up, or your command really heals you, the plugin has to run inside a server while you play. This page sets one up for you: no folders to create, no files to copy.

Here is what happens when you press Start server:

  1. Your plugins are compiled

    Every example you picked is compiled fresh, exactly like the Compile Lab does, and packed into a jar. Jars you built in the Compile Lab are added as they are.

  2. Paper 26.3 is downloaded once

    The first start downloads the official Paper 26.3 server from PaperMC and checks that the file is not damaged. Later starts reuse it.

  3. The server starts

    Paper loads your plugins, creates a world and prints Done in the server console. The first start takes a minute or two.

  4. You join and play

    Open Minecraft 26.3 and connect to localhost. Your plugins are running.

The test server

Loading the Test Server...

Joining from Minecraft

The server runs on your own PC, so the address is localhost, which always means "this computer". The game must be version 26.3, the same as the server.

In Minecraft, click Multiplayer, then Direct Connection, type localhost and click Join Server.

Once you are in, most plugin commands need permission. Type op and your Minecraft name in the console on this page (for example op Steve) to make yourself an operator, who may use every command.

Reading the console

The console shows the server's log as it happens. The lines that matter most when you test a plugin look like this:

Server console
[14:02:10 INFO]: [FirstListener] Loading server plugin FirstListener v1.0.0[14:02:11 INFO]: [FirstListener] Enabling FirstListener v1.0.0[14:02:15 INFO]: Done (4.218s)! For help, type "help"[14:03:02 INFO]: Steve joined the game
  • Loading and Enabling with your plugin's name mean Paper found your jar and started it. If your plugin is missing here, the plugin.yml is usually wrong.
  • Done means the server is ready for players.
  • Lines in gold are warnings, lines in red are errors. A red error with a list of at lines under it is a stack trace: your plugin crashed somewhere. Paste it into the Error Doctor to find out why.

Type plugins in the console to list every loaded plugin. Green names are running; red names failed to start.

When something goes wrong

You seeWhat it meansWhat to do
Port 25565 is already in useAnother Minecraft server is already running on this PC.Stop the other one (for example IntelliJ's Run Paper Server), then start again.
Could not download PaperThe PC is offline or PaperMC could not be reached.Check your internet connection and press Start again. This only matters for the first start.
Java 25 was not foundPaper 26.3 needs Java 25 or newer.Install Java 25 as shown on the Toolbox page, then restart Start Guide.cmd.
A plugin did not compileOne of the picked plugins has a compiler error.Open it in the Compile Lab, fix the error, and try again.
A version message such as Incompatible clientYour Minecraft version is not 26.3.Pick version 26.3 in the Minecraft Launcher.

Live mode only

Running a server needs Java on your PC, so this page only works in live mode: open the guide by double-clicking Start Guide.cmd. The server lives in the guide's own data folder, not in your projects, and closing the Start Guide window stops it. When you are ready for a server of your own, Build and run shows how IntelliJ's Run Paper Server does the same job for your real projects.