Fix "Address already in use" on a game server

Two things want the same port and only one can have it. The usual causes are an old process that has not finished dying and a plugin quietly claiming a port of its own.

6 min read · Updated Oct 21, 2026 · By GuavaHost Team

The message takes a few shapes depending on the game:

java.net.BindException: Address already in use
**** FAILED TO BIND TO PORT!
The exception was: java.net.BindException: Address already in use
Perhaps a server is already running on that port?

Other games say it less politely, sometimes just "failed to bind" followed by a number. The number is the port.

What a port is, briefly

Your server has one IP address, the numeric address of the machine it runs on. A port is a numbered door on that address. Your Minecraft server might be at 123.45.67.89:25565, where 25565 is the port.

A port can only be held by one process at a time. When your server starts, it asks the system for its port. If something already has it, the request fails and the server stops, because a game server with no port is useless.

Finding your server IP and port covers where to read yours.

Cause 1: the old process has not let go

By far the most common, and the easiest to fix.

When you stop a server, the game saves the world, closes its files and exits. On a big modded world that takes a while. If you press Start during that window, the new process finds the old one still holding the port.

What it looks like: you stopped the server, started it again quickly, and it failed. Wait thirty seconds and it works.

The fix:

1. Press Stop at the top of the server page.
2. Watch the status until it reads Offline, not Stopping.
3. Watch the Console for the game's own goodbye line, such as Stopping server followed by the process ending.
4. Then press Start.

If the status sits on Stopping for more than a minute or two, the process is hung rather than busy. Force stop stops it immediately rather than asking nicely, which is the right tool here but not for everyday use, because it skips the save. Start, stop and restart your server explains when each button is appropriate.

A hang on shutdown is worth investigating on its own, because it usually means a plugin or mod is stuck mid-save. Read the last lines of the Console before you force anything, because the game often names what it is waiting on.

Cause 2: a plugin wants its own port

This is the one that catches people out, because the error can name a port you did not know was involved.

Plenty of plugins and mods run a small service of their own, with its own port, separate from the game:

The problem is that those defaults do not belong to you. Your server owns a specific set of ports, and a plugin trying to bind 8123 because that is its default will fail if 8123 is not yours, or if something else on the machine already has it.

Two plugins choosing the same default is the other version of this. Two map plugins both wanting 8123, for instance, or a voice plugin and Geyser both wanting the game port for UDP.

The fix: give each one a port you own

The Ports & network card on your server's Overview tab lists every port your server has. The Server address at the top is your main game port, and anything else appears under Other ports, each with a copy button and a label such as "RCON port" or "Query port" where we know what it is for.

Click Manage on that card to open the Ports & network page, where you can:

• Add a port, letting us pick the next free one or choosing from the free ports on your machine.
• Point a game feature at a port, under Game ports, for things like RCON or Query.
• Add a note so you remember which plugin owns which number.

Then set the plugin's config to the port you added, not to its default. Each plugin names the field differently, but it is always in its own config file on the Files tab:

# Geyser config.yml
bedrock:
  port: 19132

# Dynmap configuration.txt
webserver-port: 8123

Change the number to one of yours, save, and restart the server. Port changes apply the next time the server starts.

Add and manage extra ports for your server covers the whole flow, including the per-server limit and removing a port you no longer use. Of the specific cases, The Bedrock port on a Geyser server is the one people get wrong most often.

One detail worth knowing: TCP and UDP are separate protocols, and a port number is separate for each. A number used for TCP by the game and for UDP by a voice plugin is not actually a conflict, which is why a voice plugin can often share the game port.

Cause 3: two servers, one port

If you run more than one server, check that they are not both set to the same port. Each server has its own allocation, but a config file copied from one to the other brings the old port number with it.

This is the usual outcome of copying a server.properties across during a migration. Check server-port after any file copy:

server-port=25565

It must match the port your server actually owns. If it does not, the server either fails to bind or binds a port nobody can reach. Change your Minecraft server port covers how the file and the allocation relate, and it is worth re-checking after any move between hosts.

A routine that clears it

1. Press Stop and wait for Offline, not Stopping.
2. Press Start and read the Console. If it binds, you are done.
3. If it fails again, read the port number in the error.
4. Check whether that number is one of yours in the Ports & network card.
5. If it is not, find which plugin wants it and point that plugin at a port you own.
6. If it is yours, something else is holding it. Use Force stop, wait, and start again.

Common questions

Why does Address already in use happen right after I restart?

Because the old process had not finished shutting down when the new one tried to claim the port. Saving a large world takes time, so wait for the status to read Offline rather than Stopping before you press Start again.

Can two servers use the same port?

No, not on the same machine at the same time. Each server needs its own port, which is why copying a config file from one server to another and leaving the old port in it causes this error.

A plugin says it cannot bind its default port. What do I change?

Add a port to your server from the Ports & network page, then change the plugin's own config to that number instead of its default. The default belongs to nobody in particular, so it is only usable if it happens to be one of yours.

Does Force stop damage my world?

It can, because it stops the process immediately instead of letting it save. Use Stop normally and keep Force stop for a server that is genuinely hung, and make sure you have a recent backup either way.

Still stuck? Jump into our Discord at discord.gg/GuavaHost and the team will help you out.

• ports
• startup
• troubleshooting
• minecraft
• plugins

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