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.

FiveM Server Won't Start – FXServer, License Key & Logs

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Server crashed – artifact	Outdated artifacts	Load latest recommended artifacts in txAdmin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

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FiveM Server Won't Start – FXServer, License Key & Logs

Error → cause → fix

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