Mindustry Server Troubleshooting

Mindustry Server Troubleshooting

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Server Not Appearing in the Browser

Check 1 — Both TCP and UDP open

Mindustry requires both TCP and UDP on port 6567. Forwarding only one protocol will prevent the server from being discovered.

sudo ufw allow 6567/tcp
sudo ufw allow 6567/udp
sudo ufw reload

Check 2 — Cloud/VPS provider security group

If you're on AWS, DigitalOcean, Vultr, Hetzner etc., there's often a cloud-level firewall separate from the OS firewall. Open port 6567 TCP and UDP in your provider's control panel as well.

Check 3 — Server version mismatch with the index

The public server browser only shows servers running a version close to the current release. Make sure your server JAR is up to date.

Direct connection workaround:

While you sort out the browser listing, players can connect directly:

1. Mindustry → Play → Join Game → Add Server
2. Enter YOUR_IP:6567

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Players Stuck on "Connecting..."

The single most common cause: UDP 6567 is not forwarded. Many firewalls handle TCP and UDP as entirely separate rules — a TCP-only rule does nothing for UDP traffic.

Confirm both are open and test from an external machine:

# Test TCP
nc -zv YOUR_IP 6567

# Test UDP (needs nmap)
nmap -sU -p 6567 YOUR_IP

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"Mod Mismatch" When Connecting

Server and client have different content mods installed (or different versions of the same mod).

Fix:

1. Check which .zip files are in config/mods/ on the server
2. Make sure every player has the exact same mod version installed via the in-game Mod Browser
3. Version numbers in the filename matter — ContentMod-v1.2.zip ≠ ContentMod-v1.3.zip

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"Version Mismatch" When Connecting

The server and client are running different Mindustry game versions. Mindustry updates frequently — a client on v157 cannot connect to a server on v155.

Fix: Update the server JAR:

sudo systemctl stop mindustry
wget -O server-release.jar \
  https://github.com/Anuken/Mindustry/releases/latest/download/server-release.jar
sudo systemctl start mindustry

Players must also update their client to the same version.

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Server Crashes on Startup

Check the console output or journal:

journalctl -u mindustry -n 50

Common causes:

• Plugin crash: A .jar or .js in config/mods/ is incompatible with the server version. Remove all mods, restart, add them back one by one to find the culprit.
• Wrong Java version: Run java -version. Mindustry requires Java 11 or newer.
• Corrupt JAR: Re-download server-release.jar from GitHub.

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Map Not Found / host Command Fails

[ERR] No map found with name: MyMap

• Confirm the .msav file is in config/maps/ (not the server root)
• Map names are case-sensitive on Linux — mymap ≠ MyMap
• Run maps to see exactly how the server sees the filename

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Server Runs But No Players Can Join (Same Network)

Mindustry counts all players on the same local network as one. Players on the same LAN as the server should connect via direct IP (Play → Join Game → Add Server → IP:6567), not via the public server list.

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Performance: Server Lagging with Many Players

• Upgrade CPU (Mindustry's server is mostly single-threaded for game logic)
• Reduce map size — larger maps with more buildings increase CPU load
• Lower player limit: config maxConnections 10
• Check RAM usage; ensure at least 512 MB free for the JVM