Troubleshooting

The most common issues on a Core Keeper server, and how to fix them. In every case, the panel Console is your first tool: read the last lines shown before the stop or error.

The server won't start

After adding a mod

A mod that doesn't support dedicated servers, doesn't match your game version, or is missing a dependency often blocks startup.

1. Stop the server
2. Remove the last mod you added from the Mods/ folder
3. Restart
4. If the server starts again, that mod is the culprit: check on its mod.io page that it supports dedicated servers, its version and its dependencies

See Install mods.

After a game update

A Core Keeper update can make some mods incompatible until their authors update them. Temporarily remove the affected mods, or restore a backup from the Backups tab.

Not enough memory

If the server stops without a clear error, or restarts in a loop while the world is heavily explored, with many players or mods, your plan's RAM may be maxed out. Check usage in the panel and see Lag and resources.

Modified server files

The dedicated server runs natively on Linux with files installed and maintained by YorkHost. Don't replace the game files (executables, libraries, the CoreKeeperServer_Data folder apart from Mods/) with those from another install, such as the ones from your Windows PC. If you're unsure about the integrity of the install, contact support before any reinstall, after backing up your world.

The Game ID doesn't show up

• Wait for startup to finish: the Game ID is only shown once the server is ready.
• Look in the file: depending on the version, it's also written to a text file at the root of the server, usually GameID.txt (Files tab).
• Scroll up in the console: it may have scrolled past among other startup lines.
• If the server stops before showing the Game ID, it's a startup issue: see The server won't start.

Players can't join

Symptom	Likely cause	Fix
Game not found with the Game ID	Game ID miscopied, or changed since a restart	Copy the Game ID shown in the console (or GameID.txt) again and share the new value
Game not found right after startup	Server not ready yet	Wait until the console shows the Game ID before joining
Connection refused because of a version mismatch	Client and server on different versions	Update the game on Steam and restart the server; if the server stays on the old version, contact support
Disconnected while loading, missing items	Different mods between the server and players	Same mods, same version for everyone (see Install mods)
Server full	Maximum number of players reached	Raise the cap in the Startup tab (see Player count)
Console player	Cross-platform play not guaranteed on a dedicated server	Our servers are built for the PC (Steam) version: contact support
Only one player stuck, the others get in	Connection issue on the player's side	Restart the game and Steam, check the player's internet connection

No ports to open

Joining with the Game ID doesn't require opening any ports on the player's side. On the server side, don't change ports manually: port opening is handled by YorkHost. See Are all ports open? and Unable to connect to the server.

The imported world doesn't load

• A new world is generated instead: the file doesn't have the right number or isn't in the right folder. It must be in worlds/ and match the slot loaded by the server, for example 0.world.gzip. See Import a world.
• The server stops while loading: the file may be incomplete (copied while the game was running) or come from a newer game version than the server. Copy it again with the game closed and check that the server is up to date.
• The world uses mods: install the same mods on the server before loading it.
• Wrong mode or seed: an imported world keeps its original mode; the Startup tab settings don't change it.

Lag and resources

Core Keeper is lightweight, but the load grows as the game goes on:

1. Explored area: the more of the world has been explored, the more areas the server has to handle.
2. Scattered players: players each in a different corner of the world multiply the active areas.
3. Large automated setups: many conveyors, drills or farms running at the same time.
4. Mods and a player cap raised above 8.

To ease the load on the server:

• Restart regularly, for example every night at an off-peak time, with an automatic restart from the Schedules tab
• Remove mods you don't need
• Keep the maximum player count in line with your plan

If RAM or CPU stay maxed out anyway, a bigger plan is justified (see Getting started). To analyse resource usage, see also Performance debugging.

Still stuck?

Contact support 7 days a week on Discord or through your client area, including:

• your server name
• what you changed right before the issue (mod, world import, update)
• the last console lines at the time of the error

Don't share your Game ID publicly

If you paste console lines in a public channel, hide the Game ID: it gives access to your server.