# Valheim Server Won't Start – Dedicated, Mods & Port 2456

Valheim dedicated server won't start? Port 2456–2458 UDP, BepInEx/mods, world backup & SteamCMD – Valheim troubleshooting.

**Quick answer:** Valheim won't start: open **ports 2456–2458 UDP**, check **world backup** and **SteamCMD validate** after updates.

**If you landed here:** Valheim dedicated crashes on start, world won't load or server restart loops.

## Related

- [Valheim won't connect](/en/gameserver/valheim/verbindet-nicht)
- [Install Valheim](/en/gameserver/valheim/installation)