Minecraft: connection to the server failedThe most common error messages and what is really behind them

Published on October 20, 2026

First: check address and server status

Before you dig into the error message, two checks that settle half of all cases:

• Is the server running at all? In the console in the web interface, the start must have completed ("Done"). If it does not start at all, Server does not start helps.
• Is the address right? The server address consists of IP and port and is shown in the web interface. Without the port, the client tries the default port - which fails if your server runs on a different port.

If you would rather enter your own domain instead of IP:port, set up an SRV record for it.

Connection refused

The client usually shows io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused. The message means: the computer is reachable, but nobody is answering on this port.

• The server is not running or is still starting up.
• The port in the address does not match the one the server uses.
• The server crashed after an error - then the cause is in the log.

Check the console first: if it says "Done", the server is running, and it is the address. If it shows nothing or an error message, it is the server.

Connection timed out

Unlike "refused", no answer comes back at all here. Typical triggers:

• Wrong IP - a typo or an outdated address that was written down.
• Local firewall or network block on the player's side, often in school and company networks.
• DNS problem, if your own domain is used and the entry is not (or no longer) correct.

Cross-check: if another player from a different network connects without problems, it is down to the side of the person who cannot get in - not the server. More on network causes in Ports & firewall.

Outdated client / Outdated server

Messages such as Outdated client! Please use 1.21 or Outdated server! I'm still on 1.20.4 are unambiguous: client and server are running different Minecraft versions.

The text always names the server's version. Set the same version in the launcher profile - or raise the server to the desired version, as described in Change the version. Keep in mind that plugins and mods must match the new version.

Failed to verify username

This message comes from Mojang authentication. Possible causes:

• The player is not (or no longer) logged in correctly in the launcher - log out and back in once.
• The authentication services are temporarily disrupted - then it affects all players at the same time.
• The server is set to online-mode=true and the client does not use a valid account.

The online-mode value is in server.properties. Switching it off removes the check and opens the server to any name - that is a security risk and not a solution to this problem.

Rejected: whitelist, ban or full server

If the connection is established and immediately disconnected, the server is answering deliberately:

• You are not white-listed on this server! - the name is missing from the list. See Set up a whitelist.
• You are banned from this server - an entry in banned-players.json or banned-ips.json.
• The server is full - max-players in server.properties has been reached.

These three cases are not errors but a decision by the server - the solution lies in the configuration in each case.

Bedrock players cannot get onto the Java server

Java and Bedrock are two separate editions and not compatible without a bridge. A Bedrock client cannot enter a Java server directly, no matter how correct the address is.

The bridge is called Geyser (plus Floodgate) and is installed on the Java server. How to do it is described in Set up crossplay; the differences between the editions are explained in Java vs. Bedrock.

Frequently asked questions