How to connect to your server — and fix it when you can’t

Every Cobbly server gets its own address of the form yourname.cobbly.net. That address is all anyone needs to join — there is no IP to look up and no port to remember. This page covers the normal way in, and then every error message people actually run into, with what each one means and what fixes it.

Connecting the normal way

1. Copy your address from the dashboard card, or from the top of the server page.
2. Open Minecraft: Java Edition and go to Multiplayer → Add Server.
3. Paste the address into Server Address. Give it any name you like.
4. Leave the port off. Typing :25565 on the end does no harm, but any other port will not work.
5. Press Done, then double-click the server to join.

Your friends join the same way, with the same address. If you would rather not hand it to everyone, turn on the whitelist first — see Controlling who can join.

What the server list tells you

Minecraft pings every server in your list, and Cobbly answers that ping even when your server is not running. So the list shows you the real state instead of a red "Can’t connect" cross:

• Sleeping — nobody has played for a while, so it stopped to free its slot. Joining wakes it. See How sleeping servers work.
• Starting — it is booting. Give it a moment and refresh.
• Queue #3 (or another number) — every shared slot is busy. Your server is in line and starts on its own as soon as one frees up.
• The normal player count and message of the day — it is running, and you can join straight away.

Java Edition only

Cobbly runs Java Edition servers. Bedrock Edition — phones, consoles, the Windows Store version — uses a different network protocol and cannot join a Java server, so there is no address to type into Bedrock that will work.

Kicked with "Starting up…" or "Your server is queued"

This is what waking a sleeping server looks like. Your first attempt starts the server and disconnects you with a message saying so. Wait a moment and connect again. The first boot of a particular version on a machine is slower, because the server software has to be fetched first; after that it is quicker. Modded servers and modpacks take longest — a big pack can need a few minutes before it accepts players.

Error: "Failed to verify username" or "Invalid session"

This one is about your Minecraft login, not the server. Minecraft checks every player with Mojang’s account servers, and your launcher’s session has expired or is out of date. Fully close Minecraft and the launcher, open the launcher again, and sign out and back in if that does not fix it. It is also what a player on a non-premium ("cracked") client sees — that is a server setting, covered in Minecraft server offline mode.

Error: "Outdated client" or "Outdated server"

Your game and the server are on different Minecraft versions. The message names the version the server expects. Either switch your launcher to that version (Installations → New installation, pick the version), or change the server’s version on the Software tab while it is stopped. Changing the server to an older version than its world was made on is not safe — Minecraft does not support downgrading a world.

Error: "You are not white-listed on this server"

The whitelist is on and your exact username is not on it. The owner adds you from the Players tab. On a free server the whitelist is also checked before the server wakes, so a player who is not on it cannot start it either.

Error: "Mod rejections", "Mismatched mod channel list" or "Incompatible client"

On a modded server, everyone needs the same mod loader, the same mods and the same versions as the server. The easiest way to match exactly is for everyone to install the same modpack at the same version through the CurseForge app. For a hand-picked mod list, compare the mods folder in the server’s Files tab with your own.

Error: "Unknown host" or "Can’t resolve hostname"

Minecraft could not find the address at all. Almost always a typo: check the spelling against the dashboard, and make sure there is no space before or after it. If the address is right and it still fails, your network’s DNS may be blocking or caching it — try another network, such as a phone hotspot, to confirm.

Error: "Connection timed out" or "Connection refused"

Usually the server was still booting, or you tried to join the moment it went to sleep. Wait a minute and try again. School and work networks sometimes block Minecraft entirely; if it works from another network, that is the cause.

Still stuck?

Open the server page and check its status. If it says Crashed, the server itself failed to start — Why won’t my Minecraft server start? walks through reading the console and fixing the common causes. Anything else, the support page has the ways to reach us.