Core Keeper Server Troubleshooting
This checklist separates the problems that look alike: an old Game ID, a stopped dedicated-server process, a version mismatch, a blocked network, a bad save, and a mod that no longer loads. Start with the smallest reversible test and keep the world backup untouched until the group can join again.
Last verified: September 1, 2026. Use the Game ID connection guide for a player who types a value and sees no response. Pugstorm's official FAQ is the source for the supported join flow and save locations.
Quick triage table
| Symptom | Likely boundary | Safe first test |
|---|---|---|
| Nothing happens after entering a “password” | Wrong join method or stale Game ID | Open Join Game, restart the Dedicated Server tool, and enter the newly printed Game ID. |
| Join begins but never finishes | Build mismatch or network path | Update Steam and the Steam Tools app, then test once from the same network and once externally. |
| Only one platform cannot join | Platform support | PC storefronts can play together; the FAQ says PC/console cross-platform crossplay is unavailable. |
| World fails after a mod or update | Changed content or save state | Restore the clean backup and reproduce without mods before changing files again. |
| Everyone reports lag after a patch | Version or world-load regression | Record the build, player count, world size/progression, and server log; do not claim a universal RAM or port fix. |
Connection and Game ID checks
- Launch Core Keeper Dedicated Server from Steam > Tools.
- Choose Launch Dedicated Server, click Play, and wait for the command window to print a Game ID.
- Keep the process running while the player chooses Join Game and enters that current ID.
- Restart both client and server if the ID was copied before initialization finished.
The official dedicated-server announcement says the supported flow does not require port forwarding. A local firewall, VPN, filtered network, or CGNAT can still affect a particular connection; compare local and external tests and capture the result rather than opening arbitrary ports.
Version and platform checks
- Update the game and Dedicated Server tool together after an official patch.
- Have players fully restart Steam and Core Keeper so an old process is not holding a stale build.
- Keep all clients on the same PC storefront family when testing. Cross-platform PC/console play is not supported by the current FAQ.
- Test a vanilla copy before investigating Workshop items or community mods.
Changed in 1.3.0.3 (29 September 2026): the patch notes list a Linux fix for C# exceptions that could crash the game with a segfault instead of being handled. They name the game rather than the server, but the dedicated server app 1963720 also moved to build 25537714 that morning, so if a Linux server has been crashing with a segfault, update it before debugging anything else. For modded servers, the same patch raised the ghost component cap from 256 to 512, and a mod that adds more required materials than the game's cap no longer floods the log with errors that lag the game.
World backups and recovery
Back up before moving, deleting, or repairing files. Pugstorm lists these locations:
| Data | Windows | Linux |
|---|---|---|
| Player saves/backups | C:\Users\[USERNAME]\AppData\LocalLow\Pugstorm\Core Keeper\Steam\[STEAM ID] | ~/.config/unity3d/Pugstorm/Core Keeper/Steam/[STEAM ID] |
| Dedicated worlds | C:\Users\[USERNAME]\AppData\LocalLow\Pugstorm\Core Keeper\DedicatedServer\worlds | ~/.config/unity3d/Pugstorm/Core Keeper/DedicatedServer/worlds |
- Stop the server cleanly with
q. - Copy the relevant directory to a dated backup location.
- Try the most recent known-good copy on the current server build.
- Keep the original untouched until players have joined, saved, and rejoined.
Performance and patch-lag evidence
Do not paste an invented server.cfg, player-limit key, or universal port into a Core Keeper support answer. Instead record CPU/memory/disk usage, player count, explored-world size, mod list, build numbers, and the exact time a save or area load stalls. A recent community patch-lag report is a useful lead, not proof of a general regression.
Mod isolation
- Disable all mods and confirm the clean world joins.
- Restore one mod at a time from the documented mod/Workshop workflow.
- If a mod breaks startup or joining, revert the newest change and check its current game-build requirements.
- Keep a written mod list and backup so another admin can reproduce the test.
Evidence to collect before asking for help
- Game and Dedicated Server build numbers.
- Fresh Game ID timestamp and the exact Join Game screen used.
- Whether local and external players fail in the same way.
- Server console output, client logs, and the last successful save time.
- World backup identifier, mod list, and the first step that changed the outcome.
Related Core Keeper guides
- Dedicated server setup
- Game ID and connection troubleshooting
- Mods and Workshop rollout
- Admin and chat commands
- Server cost and sizing
Need fewer home-network and process variables? Use managed Core Keeper hosting with an always-on process and backups, while keeping this evidence-first workflow for mods and updates.