# American Truck Simulator Server Troubleshooting (/docs/american-truck-simulator/troubleshooting)



Common Issues [#common-issues]

"Server packages file not found" [#server-packages-file-not-found]

`server_packages.sii` and `server_packages.dat` are missing from the server directory. These are **required** for the server to start.

**Fix:** Export them from your game client — see [Mod Setup](/docs/american-truck-simulator/mod-setup).

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Can't Connect / Version Mismatch [#cant-connect--version-mismatch]

The game client and server must be on the **exact same version**. Server updates can lag behind client updates by days.

**Fix:** Downgrade your game client via Steam Betas tab, or wait for the server update. See [Version Mismatch](/docs/american-truck-simulator/version-mismatch).

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Server Not in Session Browser [#server-not-in-session-browser]

Port forwarding is not configured. The ATS server does **not** handle NAT punching.

**Fix:** Forward TCP+UDP on ports 27015 and 27016. See [Ports Reference](/docs/american-truck-simulator/ports-reference).

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Server Crashes on Startup with GSLT [#server-crashes-on-startup-with-gslt]

Wrong App ID used when creating the GSLT token.

**Fix:** The GSLT must use App ID **270880** (base game), NOT 2239530 (server). Regenerate at [Steam Game Server Management](https://steamcommunity.com/dev/managegameservers).

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"Error reason 7" or "Error reason 8" Disconnections [#error-reason-7-or-error-reason-8-disconnections]

Server losing its Steam connection.

**Fix:** Check network stability. Verify the GSLT token is still valid. Regenerate if expired.

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Mods Not Working [#mods-not-working]

**Fix:** Re-export `server_packages` after any mod changes and re-upload both files. Players must have the same mods installed.

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Config File Not Generating [#config-file-not-generating]

**Fix:** Run the server executable once — it auto-creates `server_config.sii` on first launch.

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> 💡 **Tip:** Check `server.log.txt` in the server directory for detailed error messages.

Related Guides [#related-guides]

* [Server Configuration](/docs/american-truck-simulator/server-config)
* [Mod Setup](/docs/american-truck-simulator/mod-setup)
* [GSLT Token](/docs/american-truck-simulator/gslt-token)
* [Version Mismatch](/docs/american-truck-simulator/version-mismatch)