How to Troubleshoot a Game Server That Won't Start

Check the Logs First

Logs tell you exactly what went wrong:

• Minecraft: logs/latest.log in server directory
• Terraria/TShock: tshock/logs/ or console output
• Valheim: console output or ~/.config/unity3d/IronGate/
• systemd services: journalctl -u servicename -n 50

Read the LAST error message — it's usually the cause.

Common Errors

• Port already in use: Another process is using the port. Find it: ss -tlnp | grep PORT
• EULA not accepted: Minecraft requires eula=true in eula.txt
• Java version wrong: Minecraft 1.20+ needs Java 17+, Paper 1.21+ needs Java 21
• Missing files: Verify all server files are present and not corrupted
• Permission denied: Check file ownership matches the service user

Port Conflicts

# Find what's using a port
ss -tlnp | grep 25565
# Or on Windows:
netstat -ano | findstr :25565

# Kill the process if needed
kill -9   # Linux
taskkill /PID  /F  # Windows

Memory Issues

• OOM Killer: Linux kills processes that use too much memory. Check: dmesg | grep -i oom
• Java heap too small: increase -Xmx in your start command
• Java heap too large: don't allocate more RAM than your system has available minus 1-2GB

File Permission Issues

# Fix ownership (Linux)
chown -R minecraft:minecraft /opt/minecraft/

# Fix executable permission
chmod +x ./start.sh
chmod +x ./TShock.Server

Firewall Blocking

# Check if port is open (Linux)
ss -tlnp | grep LISTEN

# Allow through ufw
ufw allow 25565/tcp

# Windows: check Windows Defender Firewall
# Allow javaw.exe or the specific port

When to Reinstall

If nothing else works:

• Back up your world/data files first
• Delete the server directory (except worlds/data)
• Re-download the server files
• Restore your world/data files
• This fixes corrupt installations without losing progress

← Back to Knowledge Base