Troubleshooting

When a server fails, SpawnLoft reads the console and names the cause wherever the failure surfaces: a strip under the server's vitals in the panel, advice under a failed spawnloft start, spawnloft why <name> from a terminal, and the Discord webhook message for a crash. Anything it does not recognise stays a stack trace, honestly, rather than being guessed at.

These are the failures it recognises, and the way out of each.

The port is already taken

Something else is listening on this server's port, usually another server or another copy of this one. spawnloft list shows who. Change the port under Settings if both should run at once.

The EULA is not accepted

Set eula=true in the server folder's eula.txt (see Minecraft's EULA) and start again. Servers SpawnLoft creates ask at creation time.

Java is too old for this server

The server is built for a newer Java than the one that launched it. Install the Java it names and, if several are installed, point this server at it: Settings in the panel, or spawnloft set <name> java=<path-to-java>. Current Minecraft needs Java 25, 1.21 needs 21, 1.18 to 1.20.4 need 17.

The server ran out of memory

It has its configured memory and wants more. Raise it under Settings, next to Java. Modded servers usually want 4G or more, and the machine has to have that to give.

The disk is full

The drive this server lives on has no room left, so saves and logs are failing. Free space, or move the data folder onto a drive that has some under Settings. spawnloft prune thins old snapshots.

A plugin is missing a dependency

A plugin depends on another plugin that is not installed; the lines above the error name it. Install the missing one from the Plugins tab, or disable the one that wants it.

A mod is missing a dependency

A mod needs another mod that is not installed. Install it from the Mods tab. For most Fabric mods that means Fabric API first.

Two plugins claim the same name

Two jars in the plugins folder provide the same plugin, usually an old copy beside a new one, or WorldEdit installed beside FAWE, which already provides it. Disable one of them in the Plugins tab.

The world failed to load

Part of the world data would not read back, usually after a hard power-off mid-save. Restore the latest snapshot from the Backups tab. spawnloft verify proves which snapshots are whole.

Something in the world crashed the server

An entity or block crashed the server mid-tick. Minecraft's own crash report names the exact thing and where it stands, and the panel links to it beside the diagnosis. If it repeats, that report is what the responsible plugin or mod's author needs.

The server stalled and the watchdog stopped it

A tick took so long the server declared itself stuck: heavy world generation, a plugin doing too much at once, or the machine out of breath. The thread dump above the shutdown names what it was doing. More memory or fewer chunks loaded usually helps.

The server jar is missing

Java could not find the server jar. Re-download it, with spawnloft upgrade for Paper or by choosing a jar again under Settings, or restore the folder from a snapshot.

Other things that look like failures

A database will not start on Linux. Managed MySQL needs libaio, libnuma and ncurses. SpawnLoft fetches them from your distribution without sudo; where that cannot work it prints the command to run. Managed MySQL is not offered on arm64. See Downloads & platforms.

Scheduled tasks stopped after I logged out (Linux). systemd user timers stop at logout unless lingering is on. Run spawnloft task linger on.

spawnloft doctor reports RCON reachable from the internet. This machine has a public address and no active firewall, and Minecraft cannot bind RCON separately from the game port. Enable a firewall that blocks incoming connections except the game port, or set server-ip=127.0.0.1 if nobody else needs to join. See Security.

An AI assistant's config change did nothing. A plugin applies configuration when it reloads, often through <plugin> reload, or at the next restart, and some plugins write their configuration back when they stop. Restart the server, then check the file. To undo a change, restore its before-edit_config_… snapshot in Backups.

Windows protected your PC. SmartScreen, not a problem with the installer. More info, then Run anyway. See Questions.

The server says stale. Its supervisor died, usually because the machine restarted. SpawnLoft cleans it up on the next read; press Start.

The server says orphaned. A Java process outlived its supervisor. Kill cleans it up, then Start.

A crashed server keeps restarting, then stops. That is auto-restart doing its job: three crashes in ten minutes and it stays down saying why, so a broken plugin cannot grind the machine all night. The diagnosis under the vitals says what to fix.

A plugin feature that silently does nothing. Usually not SpawnLoft. Filter the console to Warnings as well as Errors; several plugins only ever report a misconfiguration at WARN, and a clean-looking log at ERROR is not a clean log.

Still stuck

Mac checks

• The app will not open: follow the Mac installation notes. Mac builds are Developer ID signed and Apple-notarized. Include the exact message, macOS version, and Mac architecture in a report.
• Managed database setup is unavailable: the app runs on macOS 13+, but managed MySQL requires macOS 15+. Older Macs can use an existing external database. See Databases.
• MySQL tools are missing: SpawnLoft checks managed binaries, Homebrew locations, /usr/local/mysql, and PATH. For an external connection, supply the tools folder with --tools if needed.
• A scheduled task did not run: confirm the task is enabled, review its run history, and keep the Mac awake and your user session logged in for the scheduled time.
• Performance is empty: start the server and allow time for the first ten-second sample. Select a range containing the run. A restart starts a new graph.
• A CLI backup is missing from the panel: the visible history refreshes every four seconds and on reopening. Wait for the archive to finish and confirm the CLI and app use the same data folder. Report it if the completed backup still does not appear.

Report a problem

Feedback → Something broke in the panel opens a GitHub issue with the version, Java, server status and panel log already filled in. For a question rather than a bug, Q&A is the place. Console → Export → Upload to mclo.gs shares the log with your account name already taken out of the paths, which is what a plugin author will ask for.