Fix common Minecraft server errors

Most Minecraft join errors come from four things: a typo in the address, a game version that doesn’t match the server, a player missing from the whitelist, or mods that don’t match. Find the message you see below. They are in order, from the ones players hit most.

Java join errors

You are not white-listed on this server!

The whitelist is on and you aren’t on it. Minecraft 26.3 and later turn the whitelist on for every new server, so this is the first error most groups see.

1. Add the player to the whitelist in Settings > Players, or type whitelist add TheirName in Console.
2. Or turn the whitelist off in Settings if you want anyone with the address to join.

Use the exact player name. Capital letters don’t matter, but typos do. See ops, whitelist and bans.

Incompatible client! Please use 26.3

Your game version doesn’t match the server’s version (the number at the end is the server’s version). Older versions say Outdated client! or Outdated server! instead. In the server list, the version shows in red.

1. In the Minecraft Launcher, open Installations, add one with the server’s version, and play with it.
2. Or change the server’s version in Settings > Game version to match your group. Back up first if you go to an older version: a world opened in a newer version can’t go back.

On Paper and Purpur, the ViaVersion plugin lets newer game versions join an older server.

Failed to verify username!

The server couldn’t check your account with Mojang.

1. Close the game and the launcher, open the launcher again and sign in.
2. Check that you own Minecraft Java Edition and play from the official launcher, or a launcher that signs in with your Microsoft account. Launchers that don’t sign in to a Microsoft account can’t join.
3. If everyone gets it at once, Mojang’s sign-in service may be down. Wait a few minutes and try again.

Can’t connect to server

In the server list, the server shows Can't connect to server. When you join, you see Failed to connect to the server, often with Connection refused on the next line.

1. Check Overview. A Stopped server doesn’t wake when someone joins. Press Start.
2. If it says Starting or Waking up, wait until it says Running.
3. Check the address: castle.play.wilderack.com, with no port.
4. Look in Console for a crash. The crash helper card tells you why.

Can’t resolve hostname

The game can’t find the address. You see Can't resolve hostname in the server list, or Unknown host when you join.

1. Copy the address from the address card on Overview and paste it in, so there’s no typo.
2. Remove any spaces, and don’t add http:// or www.
3. If you changed your server’s name recently, use the new address.

The game asks you to use your server’s address

You typed the server’s IP address instead of its name. Java servers here are found by name, so use the address from the address card, like castle.play.wilderack.com.

The server says it is waking up

The server was asleep for a long time, so waking takes longer than the game waits. Join again in about a minute. Next time it wakes in a couple of seconds.

Timed out

The connection stopped answering. This is often the player’s internet, or a server that’s overloaded.

1. Try again. Check your own connection.
2. If everyone times out, look at the graphs on Overview. Full RAM or very high CPU points to too many mods or a lag machine. See performance.
3. If it’s only one player far away, the other region may suit your group better.

You are banned from this server

An operator banned this player. To undo it, type pardon TheirName in Console, or remove them from the ban list in Settings > Players. For IP bans, use pardon-ip with the address.

The server is full!

All slots are taken. Raise the player limit in Settings (the max-players key), or let operators skip the limit with bypassesPlayerLimit in ops.json.

Multiplayer is disabled. Please check your Microsoft account settings.

The player’s Microsoft account isn’t allowed to play online. This is common for accounts under 18 in a Microsoft family group. A parent can allow multiplayer in the Microsoft Family Safety settings. Nothing on the server can change this.

Bedrock join errors

Unable to connect to world.

The game couldn’t reach the server.

1. Check that the server is Running or Sleeping on Overview. Press Start if it’s Stopped.
2. Check the boxes: the address in Server Address, and the port from the address card in Port. Not 19132, unless you have a Dedicated IP.
3. Update the game. Old versions can’t connect to servers on the newest version.
4. Turn off any VPN and try another network, like mobile data.
5. On a console, this often means the workaround tool isn’t set up yet. See consoles.

You’re not invited to play on this server.

The allowlist is on and this player isn’t on it. Bedrock servers start with it on.

1. Type allowlist add "Their Gamertag" in Console, using quotes if the gamertag has spaces.
2. Or add them in Settings > Players, or turn the allowlist off in Settings.

Could not connect: Outdated client!

The player’s game is older than the server. Update Minecraft from the device’s store and try again.

If players see The host is using an older version of Minecraft instead, the server is older than their game. Set Settings > Game version to update automatically, then restart. Bedrock servers only accept players on the same version, so keep it that way.

Wow this server is popular! Check back later to see if space opens up.

The server is full. Bedrock servers allow 10 players by default. Raise the player limit in Settings (the max-players key) and restart.

You cannot play online multiplayer because of how your Microsoft account is set up.

The player’s Microsoft account blocks multiplayer. On a child account, a parent can allow it in Microsoft Family Safety. On a console, the player may also need the console’s online membership.

The game asks to trust the server every time

Bedrock’s new connection (NetherNet) asks once whether you trust a server you join by address. If it asks after every restart, the server’s identity key changes each time. Tell us at support@wilderack.com and we’ll look into it.

Modded server errors

The disconnect screen lists missing or mismatched mods

Your mods don’t match the server’s. Fabric, NeoForge and Forge each show this a bit differently, but they all list the mods that are missing or have a different version.

1. Install the same modpack, at the same version, in your launcher. The Mods tab shows what friends need.
2. For your own mod list, match every mod that adds content, and the mod loader version too.
3. If you added extra mods of your own, remove any that add blocks or items the server doesn’t have.

The server crashes on start after adding a mod

Console names the mod that failed. The usual causes:

• The mod is for another game version, or another loader (a Fabric mod on NeoForge).
• It needs another mod (a dependency) that isn’t installed, such as Fabric API.
• Two mods don’t work together.

Remove the last mod you added, or restore the backup made before the install in Backups.

java.lang.OutOfMemoryError: Java heap space

The server ran out of RAM. Big modpacks, many players and a high view distance all add up. Move to a bigger plan, lower view-distance, or remove heavy mods. The modpack guide has a RAM table.

The server won’t start

You need to agree to the EULA in order to run the server. Go to eula.txt for more info.

eula.txt doesn’t say eula=true. We set it when you accept the Minecraft EULA at create. If the file was deleted or changed, open eula.txt in Files, read the EULA at minecraft.net/eula, and set eula=true if you agree.

UnsupportedClassVersionError

You see a line like has been compiled by a more recent version of the Java Runtime. The server needs a newer Java. Minecraft 26.1 and later need Java 25, and 1.20.5 to 1.21.11 need Java 21. The panel picks the right Java for the version in Settings > Game version. You only see this if you uploaded your own server jar, so pick the version there instead.

FAILED TO BIND TO PORT!

The server couldn’t use its port. This happens when server-port or server-ip in server.properties was changed. Put them back as they were, or restore the file from a backup in Files, then restart.