Quick answer: Read the FXServer console or txAdmin logs first. Top 3 causes: missing/wrong license key, wrong artifact version, port 30120 blocked.
If you landed here: FXServer crashes on start, hangs at "Authenticating server license key" or players see "Connection failed".
Error → cause → fix
| Symptom / log | Cause | Fix |
|---|---|---|
| Could not authenticate license key | Missing/wrong key/IP changed | Create key at keymaster.fivem.net → server.cfg |
| Server crashed – artifact | Outdated artifacts | Load latest recommended artifacts in txAdmin |
| Failed to bind to port | Port 30120 in use | Kill old process or change port in cfg |
| Connection failed (client) | Firewall / port | 30120 TCP+UDP → Firewall |
| Database connection error | MySQL/MariaDB wrong | Connect database |
Related
Frequently asked questions (FAQ)
FiveM server won't start – what to check first?
Read FXServer console/txAdmin logs. Common: missing license key, wrong artifact version, port 30120 blocked, bad server.cfg line.
Could not authenticate server license key – fix?
Create server key at keymaster.fivem.net, in server.cfg: sv_licenseKey "your-key". Key is bound to your IP – generate new key on IP change.
Server starts but nobody can join?
Open port 30120 TCP+UDP in firewall/panel, check sv_endpointprivacy, OneSync settings, provider firewall – not just UFW.