IW4x Dedicated Server Troubleshooting Guide

IW4x Dedicated Server Troubleshooting Guide

This guide covers the most common problems encountered when running an IW4x dedicated server, organized by symptom. Each issue includes diagnostic steps and the most likely fixes.

Server Won't Start

"iw4x.dll not found" or "Failed to load IW4x"

The AlterWare Launcher hasn't downloaded the core DLL yet, or it got corrupted.

Fix:

cd C:\GameServers\MW2-Server
alterware-launcher.exe iw4x --update

If the file already exists but is corrupted, delete iw4x.dll first and re-run the launcher.

Crash immediately on startup (no error window)

Usually a missing Visual C++ Redistributable.

Fix:

1. Install VC++ 2010 Redistributable (x86) from Microsoft.
2. Install VC++ 2015–2019 Redistributable (x86) from Microsoft.
3. Both are required. The x86 (32-bit) versions are needed even on 64-bit Windows.

On Linux with Wine:

WINEPREFIX=~/.wine_mw2 WINEARCH=win32 winetricks vcrun2010 vcrun2019

"Could not find zone 'localized_common_mp'"

The base game files are incomplete or corrupted.

Fix: Verify the MW2 install via Steam (right-click the game → Properties → Local Files → Verify integrity). If using SteamCMD, re-run the download with validate.

Server starts but crashes after loading first map

Check userraw/logs/games_mp.log (or create it if it doesn't exist):

set g_log "logs/games_mp.log"
set logfile "2"

Look for GSC errors or "zone not found" messages just before the crash. A mod that references map files you don't have is a common cause.

Server keeps restarting in a loop

Add more verbose logging to the launch command to capture the crash reason:

iw4x.exe -dedicated +set logfile "2" +set g_logSync "2" ... > server_output.txt 2>&1

Check server_output.txt after the crash.

Server Not Appearing in Browser

This is one of the most common issues and has several possible causes. Work through these in order:

1. sv_lanonly is set to 1

set sv_lanonly "0"   // Must be 0 for public visibility

2. Firewall is blocking UDP 28960

On Windows:

netsh advfirewall firewall show rule name="IW4x Game UDP"

If the rule doesn't exist, add it:

netsh advfirewall firewall add rule name="IW4x UDP" dir=in action=allow protocol=UDP localport=28960

On Linux:

sudo ufw status | grep 28960

3. Router/NAT port forwarding not set up (home server)

Home connections are behind NAT. The router must be configured to forward UDP 28960 to your server's local IP. See the IW4x Port Forwarding Guide.

4. AlterWare Launcher is outdated

The launcher also registers the server with AlterWare's backend. Update it:

alterware-launcher.exe iw4x --update

5. party_enable is set to 1

Party mode servers behave differently in the browser. Set +set party_enable "0" in your launch command.

Verifying the server is reachable

From a different machine, test:

nc -zuv YOUR_PUBLIC_IP 28960

If the port is unreachable, the problem is networking/firewall. If it's reachable, the problem is server registration with AlterWare.

Players Can't Connect

"Server is not available" or connection timeout

• Confirm the server is running: run rcon status from a client or check the server console
• Verify UDP 28960 is open inbound and outbound in the firewall
• If on a home network, verify port forwarding is correct

Players get disconnected immediately after joining

• Possible version mismatch between client and server: update IW4x on the server and have players update their clients
• sv_securityLevel too high: try lowering it to 23 (the standard value)
• Map not found on client side: if a DLC map is in the rotation that a player doesn't have

"Bad CD key" or authentication errors

This is an IW4x-specific behavior when a client's network ID conflicts. Usually resolves itself; if persistent, the affected player should regenerate their IW4x GUID by deleting their players2/ folder in the IW4x client directory.

IW4MAdmin Can't Connect

Work through this checklist:

1. Verify the server is running and accepting connections.
2. Check rcon_password matches exactly between server.cfg and IW4MAdminSettings.json — no extra spaces, matching case.
3. Verify g_logsync "2" and logfile "2" are set in server.cfg. Without this, IW4MAdmin cannot read events.
4. Check the log file exists: navigate to userraw/logs/games_mp.log. If the file doesn't exist, IW4MAdmin can't read it — start the server, let it run through one map, then check again.
5. Confirm the Parser: must be "IW4x Parser" in IW4MAdminSettings.json.
6. Check .NET 8 Runtime is installed on the machine running IW4MAdmin.
7. Check TCP 1624 is open if you're trying to access the web panel from another machine.

IW4MAdmin logs its own errors to a log file in its installation directory. Check it for detailed error messages.

Mod Not Loading

Server runs vanilla despite fs_game being set

• Verify the fs_game value in DedicatedServer.bat — check for typos, extra quotes, or path separators
• Confirm the folder mods/[modname]/ exists inside your server directory
• On Linux, the path is case-sensitive — mods/mp_bots is different from mods/MP_Bots
• Ensure the mod folder contains at least one .iwd file

"Could not find zone" crash with mod loaded

The mod references map-specific data for a map you're trying to load that doesn't have the required IWD files. Check the mod documentation for required DLC packs.

Performance Issues

High server CPU usage

• Reduce sv_maxclients if you're running too many players for your hardware
• Bot Warfare bots increase CPU usage significantly — reduce bots_manage_fill
• Add +set com_maxfps "125" to the launch command to cap the server's physics tick rate

Players reporting lag / high ping

• Check server network bandwidth — sustained high player counts can saturate uploads
• Verify the server machine isn't running other bandwidth-heavy processes
• Check sv_timeout and sv_connectTimeout aren't set abnormally low

Server freezing temporarily ("hitch warnings")

• Reduce loaded GSC scripts if you have many
• Check available RAM — IW4x with a full server uses ~500 MB to 1 GB
• On Linux, check dmesg for OOM killer events

Log File Reference

The primary diagnostic sources:

File	Contents
userraw/logs/games_mp.log	Game events, chat, connect/disconnect
Console stdout	Startup errors, GSC compilation failures, crash info
IW4MAdmin log directory	IW4MAdmin connection and event errors

On Linux, redirect stdout to a file:

wine iw4x.exe -dedicated [...launch args...] > ~/mw2server/console.log 2>&1

Quick Diagnostic Checklist

Before posting for help, confirm:

• iw4x.dll exists and was downloaded by the AlterWare Launcher
• sv_lanonly "0" is set for a public server
• UDP 28960 is open inbound in the OS firewall
• rcon_password is set and non-empty
• g_logsync "2" and logfile "2" are set
• userraw/logs/ directory exists
• VC++ 2010 x86 and VC++ 2015–2019 x86 are installed (Windows)
• Wine is configured as win32, not win64 (Linux)

Related

• Installing Your IW4x Dedicated Server on Windows
• IW4x Server Port Forwarding and Firewall Setup
• Host an IW4x (MW2) server with DustBowl.Games