Fixes · 8 min read

Can't connect to your Minecraft server? 7 checks

What Connection timed out, Connection refused, Incompatible client and not white-listed mean on a Minecraft Java server, and the fix for each.

Last checked 11 November 2026

Short answer

Read the exact words on the error screen: they tell you where the connection failed. Connection timed out means nothing answered: a firewall dropped it, the address is wrong, or the port isn't forwarded. Connection refused means the machine answered but no server was listening on that port: it's stopped, still starting, or the port is wrong. Incompatible client or Outdated server is a version mismatch, and not white-listed means the server works and you need adding. Find your message below, then work through the checks in order.

Find your message

Minecraft shows the error in two places: in red under the server's name in the Multiplayer list, and on the screen you land on after pressing Join Server. The wording below is Minecraft Java 26.3's own.

Minecraft Java connection errors, what each means and which check fixes it
What you see	What it means	Check
Can't connect to server (in the server list)	What it meansThe list's ping got no answer from that address and port	Check1, 2, 5
Failed to connect to the server, then a line with timed out in it	What it meansNothing answered. A firewall dropped it, the address is wrong, or the port isn't forwarded	Check2, 5, 6
Failed to connect to the server, then a line with Connection refused in it	What it meansThe address answered, but nothing is listening on that port	Check1, 2
Can't resolve hostname, or Unknown host	What it meansThe name you typed doesn't exist	Check2
Incompatible client! Please use 26.3 (on Paper: Outdated client! or Outdated server! I'm still on…)	What it meansYour game and the server are on different versions	Check3
Incompatible version! (in the server list)	What it meansThe same: a version mismatch	Check3
You are not white-listed on this server! (on Paper: not whitelisted)	What it meansThe server is fine. You aren't on its whitelist	Check4
You are banned from this server	What it meansAn operator banned you or your IP address	Check4
The server is full!	What it meansIt has reached its player limit	Check4
Failed to verify username! or Invalid session	What it meansMojang's account check failed for your login	Check4
Multiplayer is disabled. Please check your Microsoft account settings.	What it meansYour account isn't allowed to play online	Check4
A list of missing or mismatched mods	What it meansYour mods don't match the server's	Check7

The line under Failed to connect to the server comes from Java, not from Minecraft, so its exact words change with your system: Connection timed out: no further information and Connection refused: no further information are two common ones. Look for the words timed out or refused. The Minecraft Wiki sums up the difference: a timeout is usually a firewall problem, and a refusal usually means the server hasn't started properly.

1. Is the server running, and has it finished starting?

A server can't be joined until it has loaded its world. Its console prints a line like this when it's ready:

Done (12.345s)! For help, type "help"

Until then, joins fail or hang. A big world, a lot of plugins or a modpack all add to the wait, and the first start after a Minecraft update takes longer while the server upgrades the world.

If the console says FAILED TO BIND TO PORT! and Perhaps a server is already running on that port?, the server never opened its port. Either a second copy is already running, something else is using the port, or server-ip in server.properties holds an address. The wiki's advice is to leave server-ip blank.

On our servers, the panel shows the server as running once that Done line appears. In our own tests on 3 October 2026, a new, empty world was ready in 19 seconds on Paper and 13 on Fabric. A Minecraft Java server of ours also stops itself after 15 minutes with nobody online unless you change that, so a server that was fine an hour ago may simply be stopped: press Start, or change Auto-stop when empty in Settings.

2. Is the address and port exactly right?

In Multiplayer, edit the server and check every character. Minecraft Java's default port is 25565, and when that's the port you can leave it off. Any other port goes after a colon:

203.0.113.10:25570

Friends in the same house use the server PC's internal address, such as 192.168.0.168. Friends elsewhere use your public address, the one a “what is my IP” site shows.
Your public address changes. Most home connections get a new one every few days to few weeks, according to the Minecraft Wiki, and the address your friends saved stops working. Check it again, or use dynamic DNS.
On a rented server, copy the address from the host's panel rather than typing it. Many hosts give each server its own port, so don't assume 25565.

3. Is everyone on the same version?

Every player's game must run the same Minecraft version as the server. A 26.3 server takes 26.3 players. On a server running Mojang's own software or Fabric, a player on the wrong version sees Incompatible client! Please use 26.3, whether their game is older or newer (much older games may word it Outdated client). Paper uses its own words: Outdated client! Please use 26.3 when the player is behind, and Outdated server! I'm still on 26.3 when the player is ahead.

The launcher updated the player. The Minecraft Launcher's Latest release moves to each new version on its own, while a server stays on the version it was set up with. To play an older version, open Installations, press New installation, pick the server's version, and play that.
Paper hasn't caught up yet. Paper builds for a new Minecraft version arrive after Mojang's release. For 26.1, Mojang released on 24 March 2026 and Paper announced its build on 26 April 2026. Until then, a Paper server stays on the previous version and its players do too.
Test versions can't join a release server. A player on one of Mojang's weekly preview builds of 26.4 has to switch back to the release.

4. Whitelist, bans, the player limit and accounts

These four all mean the connection worked and the server turned the player away, so there's nothing to fix in the network.

Not white-listed. Since Minecraft 26.3 the whitelist is on by default: Mojang's 26.3 notes say “The white-list property is now true by default”. So a new 26.3 server turns away everyone you haven't added. In the server console, type whitelist add <name> with the player's exact Java username. To let anyone in instead, set white-list=false in server.properties and restart.
Banned. pardon <name> lifts a ban on a player, and pardon-ip <address> lifts a ban on an IP address.
Full. max-players is 20 unless you change it.
Failed to verify username, or Invalid session. With online-mode=true, the default, the server checks every player's account with Mojang. Quit the game and the launcher, sign in again and retry. Launchers that skip Mojang's sign-in are refused by design. Don't turn online-mode off to get round it: the wiki warns that the whitelist then stops working, because anyone can join with any name.
Multiplayer is disabled. This one is the player's own Microsoft account, usually a child account whose settings don't allow online play. The account's parent or guardian changes it in the Microsoft account's settings; no server setting can.

server.properties explained covers each of these settings, and the server.properties generator checks a file for you.

5. On a home server: the firewall and port forwarding

If friends in your house can join but nobody outside can, the problem is between your PC and the internet. Work from the PC outwards.

The PC's firewall. On Windows, the first start shows a firewall prompt for Java (for example “OpenJDK Platform binary”). If you closed it, allow Java in Windows Security, under Firewall & network protection, then Allow an app through firewall.
A fixed internal address. Give the server PC the same internal address every time, in your router's settings. Otherwise the router can hand it a new one and the forwarding rule points at nothing.
The forwarding rule. Forward external port 25565 to the server PC's internal address, port 25565. The game uses TCP. UDP is only for the query feature, which is off unless you set enable-query=true.
Test from outside. With the server running, use a port-checker site, or join from a phone on mobile data. Some routers won't let a PC inside the house reach the house's own public address, so a test from inside can fail when everything is fine.

Don't switch the router's firewall off to test. The Minecraft Wiki explains that forwarding rules are firewall rules, so turning the firewall off disables forwarding as well, and a port checker then reaches the router instead of your PC.

6. CGNAT, a second router or a VPN

If the rule is right and outside players still time out, something past your router may be in the way.

CGNAT. Some internet providers share one public address between many homes, so a forwarded port never reaches you. Sign in to your router and find its internet (WAN) address. If it starts with anything from 100.64 to 100.127, you're behind CGNAT: that range is set aside for it by RFC 6598. If the router's address differs from what a “what is my IP” site shows, something else is translating your address too. This test is our reading of the standards, not Mojang's advice. Ask your provider for a public address, or host somewhere else.
A second router. If your router's WAN address is an internal one, such as 192.168.x.x, your modem is a router as well, and the port has to be forwarded on that one too.
A VPN or a security suite. A VPN on the server PC hides it behind the VPN's address, and some antivirus suites bring their own firewall. Switch them off one at a time to test.

7. Mods, plugins and Bedrock players

Plugins (Paper) run only on the server. Players need nothing extra.
Mods (Fabric, NeoForge, Forge) usually have to be on both sides. Every player needs the same loader, the same loader version and the same mods at the same versions as the server, apart from mods made for one side only. Forge and older NeoForge versions tend to say mismatched mod channel list; newer ones list the mods that are missing. The wording varies by loader and version, so if it's unclear, read the player's latest.log in the launcher's logs folder.
Bedrock players can't join a Java server. Minecraft on phones, consoles and the Windows edition from the Microsoft Store is Bedrock Edition. Plugins exist that bridge the two; they are third-party and need extra setup.

On a rented server

A hosted server takes checks 5 and 6 off your list: no router, no Windows firewall and no CGNAT at your end. Players still need the right address, the same version, a place on the whitelist and matching mods.

We rent Minecraft Java servers running Paper or Fabric, and modded ones running NeoForge or Forge. On ours:

Copy the Join address from the server's Overview. It's the address and the port in one.
Under Can players reach it?, press Run the checks. It pings the server from outside, as the Multiplayer list does, and shows the Minecraft version it answered with. If it works there but not for one player, the block is on that player's side: their version, their account, their network or a VPN.
Add players with whitelist add <name> in the console, or switch Whitelist off under Game → All settings.

If you're still deciding where to run one, how to host a Minecraft server compares your own PC, Realms, free hosts and renting.

Questions people ask

Why can people on my Wi-Fi join, but not friends elsewhere?

Players in your house reach the server directly, without going through your router's forwarding. Anyone outside needs the forwarding rule (check 5) and a connection that isn't behind CGNAT (check 6).

Do I need to open UDP 25565?

No. Joining uses TCP. UDP is only for the query feature, which is off by default. The wiki's tutorial says to forward both, which does no harm, but only TCP is needed to play.

The server list says Can't connect to server, but the console says it's running. Why?

The list pings the address and port you saved, so a typo, an old public address or a port that isn't forwarded all look like this. Join from inside the house with the internal address: if that works, the server is fine and the problem is the route in.

Still stuck?

On a home server, read the last lines of the server's console when a player tries to join: a refused player is usually named there with the reason. The setup guide covers the full home setup from the beginning.

On our servers, press Copy the last 200 lines above the console, then press Contact a human and paste them in, with the exact words the player sees. A person reads it, not a bot.

Game facts checked against Minecraft Java Edition 26.3 and Paper 26.3.