# When something does not work

> The server will not boot, players cannot connect, the console is quiet — where to look, and in what order.

Source: https://stygion.eu/docs/panel/reseni-potizi
Updated: 2026-08-30

The order is always the same: **what the console says**, then **what the
panel says**, and only then the machine.

## The server will not boot

Open the [console](/docs/panel/konzole) and read the first ten lines
after the banner. The answer is almost always there.

| What you see | What it is |
|---|---|
| `UnsupportedClassVersionError` | Wrong Java. Change the [image](/docs/panel/startup). |
| `-XmxM` in the command | A misspelled variable. Unknown ones render empty. |
| `Permission denied` on a file | Ownership. **Files → Change permissions**. |
| `Address already in use` | Something else holds the port. [Allocations](/docs/panel/sit). |
| Nothing for a long time after the banner | A modpack unpacking. A minute is normal. |
| `EULA` | `eula.txt`, in [files](/docs/panel/soubory). |

## Players cannot connect, but the server is up

The panel opens a port on the machine, and there its responsibility
ends. Work from the inside out:

1. **Is the server listening?** The console should say `Done` and a
   port.
2. **Is the allocation right?** [Network](/docs/panel/sit) — the first
   one is what fills `SERVER_PORT`.
3. **The machine's firewall.** The installer opened the panel's ports,
   not the game's.
4. **The router.** A port forward that did not come back after a reboot
   looks exactly like a server that is down.
5. **DNS.** A domain is not a route. If the port does not work, a domain
   will not fix it.

## The console shows nothing

First, whether the server is actually running — the state is beside its
name. Then the status at the top right of the console: `connected`,
`connecting…`, `disconnected`.

A `disconnected` that does not come back is usually a reverse proxy that
does not pass WebSockets. The panel pings every 25 seconds; a proxy with
a shorter idle timeout will still close it.

An empty console for a running server that something other than the
panel started is normal only until the next restart — the panel adopts
running servers.

## I type a command and nothing happens

Before 0.3.3 there was one usual cause: the panel had restarted in the
meantime and that closed the server's input. Since 0.3.3 it does not
happen — but a server still running from an older version is still in
that state. **Stop it and start it once** and it moves over by itself.

When a command does not arrive, the panel says so. The `> command` line
appears only once the server has taken it.

## A panel update failed

The message is the real one. Two usual causes: **nowhere to write** (the
directory holding the binary must belong to the user the panel runs as)
and **the build is gone** (a channel points at a withdrawn release for a
while). More under [Updating](/docs/panel/aktualizace).

## Before you write to support

Send this straight away — it is exactly what we would ask for:

- the panel's version (`stygion-core --version`),
- what you pressed and what happened,
- the first twenty lines of the console after the start,
- whether the server is on the master or on a [node](/docs/panel/uzly).