Common Minecraft server errors and how to fix them

Most Minecraft server problems have a short list of causes. Find your error message below.

Server won't start

• "You need to agree to the EULA": open eula.txt and change eula=false to eula=true, then start again.
• "Failed to bind to port" or "Address already in use": another program is using that port, or the port in server.properties does not match your allocation. Set server-port to the port shown in your panel.
• "Unsupported class file major version" or "UnsupportedClassVersionError": your Java is too old for the server. Newer Minecraft versions need newer Java (1.18 to 1.20.4 use Java 17, 1.20.5 and later use Java 21).
• "java.lang.OutOfMemoryError": the server ran out of RAM. Lower view-distance or upgrade your plan.

Players can't join

• "Connection timed out: no further information": the IP or port is wrong, or the server is offline.
• "Connection refused": the server is not running or the port is wrong.
• "Outdated server" or "Outdated client": the player's game version doesn't match the server.
• "You are not whitelisted on this server": add the player with /whitelist add name or turn the whitelist off.
• "Failed to verify username": Mojang's login service was unreachable or the player is using a cracked client while online-mode is true.

Lag and crashes

• "Can't keep up! Is the server overloaded?": the server is too slow for the load. See our guide on reducing Minecraft lag.
• Crashes after adding a plugin or mod: remove the last addition and check the logs or crash-reports folder.

Still stuck? Open a ticket on our Discord with a copy of your latest log and we will take a look.