Open Fortress Dedicated Server Troubleshooting
When something isn't working, start with the server console output and any error text that appears at startup. Most issues produce a clear message if you look closely.
Server Not Appearing in the Server Browser
Most likely cause: sv_lan 1
Open open_fortress/cfg/server.cfg and verify:
sv_lan 0
sv_lan 1 registers the server as LAN-only and hides it from Steam's global server browser. It will not appear publicly.
Secondary cause: UDP 27015 not forwarded
Both UDP 27015 (primary) and UDP 27005 (client port) must be open inbound through your firewall and router. If only 27015 is open, the server may appear in the browser but players fail to connect.
# Linux UFW — open both required ports
sudo ufw allow 27015/udp
sudo ufw allow 27005/udp
Also check your cloud provider's security groups if you're on a VPS — they sit above the OS firewall.
Game Mount Failures on Linux
Cause: server installed to /mnt/c/ or another Windows-mounted path
If your server console shows errors like Failed to mount game directory or similar mount errors on startup, and you're running under WSL, verify where the files are installed:
pwd # should show /home/... not /mnt/c/...
The Source engine requires POSIX-compliant file I/O. Windows paths mounted through WSL (/mnt/c/) do not satisfy this. Reinstall to a native Linux path such as /home/ofserver/sdk/.
Steam Library / steam_appid.txt Errors
If you see errors referencing the Steam app ID at startup — such as No steam_appid.txt found or the game loading as the wrong app — verify the file exists in the SDK directory:
cat /home/ofserver/sdk/steam_appid.txt
The file must contain exactly:
243750
No spaces, no newlines other than the implicit one. If the file is missing or contains a different value, create it:
echo "243750" > /home/ofserver/sdk/steam_appid.txt
SDK Beta Branch Error (Wrong Files Installed)
Cause: app_update 244310 without the -beta previous2021 flag
Source SDK 2013 MP (AppID 244310) must be installed from a specific beta branch. If you ran app_update 244310 without the branch flag, you installed the default branch which is incompatible with Open Fortress.
Re-run your SteamCMD script with the correct branch:
force_install_dir /home/ofserver/sdk
app_update 244310 -beta previous2021
The previous2021 branch is not optional — omitting it gets you the wrong set of files and OF will not launch correctly.
Players Can't Connect (Server Appears in Browser)
Cause: UDP 27005 not forwarded
The server shows up in the browser (which uses UDP 27015 for queries) but players time out when joining. This almost always means UDP 27005 is blocked.
sudo ufw allow 27005/udp
sudo ufw reload
Also forward UDP 27005 on your router if you're behind NAT.
Server Crashes Repeatedly
Cause: outdated Open Fortress files
OF is under active development. Crashes on a server that previously worked usually mean your OF files are behind the current version. Update via:
# Re-run the Beans updater, or
/home/ofserver/steamcmd/steamcmd.sh +runscript /home/ofserver/fullupdate.txt
Also confirm you're using the -autoupdate flag in your launch command — this tells srcds_run to check for updates and restart when it detects them:
./srcds_run -console -game open_fortress ... -autoupdate
SourceMod Not Loading
Check the gamedata and Open-Fortress-Tools plugin
If SourceMod loads but commands like sm version produce errors or SM behaves incorrectly:
- Verify the Open-Fortress-Tools plugin is installed:
rcon sm plugins list - Check SM error logs:
open_fortress/addons/sourcemod/logs/errors_YYYYMMDD.log - Ensure your SM build matches the Source SDK 2013 / TF2 engine, not a CS2 or CSGO build
Maps Fail to Load (Invalid Map Name)
Confirm the map file exists:
ls /home/ofserver/sdk/open_fortress/maps/ | grep dm_crossfire
If it's missing, your OF files may be incomplete. Re-run the Beans updater or re-download the OF files from SVN.
Quick Diagnostic Checklist
| Symptom | Check |
|---|---|
| Not in browser | sv_lan 0 in server.cfg; UDP 27015 open |
| Players time out on join | UDP 27005 open |
| Mount failures | Installed to /home/, not /mnt/c/ |
| Wrong app ID at startup | sdk/steam_appid.txt contains 243750 |
| SDK install corrupted | Reinstall with app_update 244310 -beta previous2021 |
| Repeated crashes | Update OF files via Beans or SteamCMD |