Start here: what build are you on?
This is not the usual throat-clearing. GRAIN ROT shipped seven patches in its first five days, and a large share of the co-op complaints still circulating describe bugs the developers already fixed. Working through settings before updating wastes your evening.
Symptom to official fix
Every row below is a real fix from the official patch notes, matched to the symptom it resolves. If your problem is here, the answer is a build number.
| What you are seeing | Fixed in |
|---|---|
| Friends cannot join when privacy is set to friends | 1.05 |
| Items destroyed when a player leaves the session | 1.04 — now dropped or moved to the lost and found crate |
| Cannot respawn because the area is blocked | 1.04 |
| A door in the ancient facilities will not open for clients | 1.03 |
| Save file loads into a black void | 1.03 |
| Key bindings do not save | 1.03 |
| Cannot load a save while offline from Steam | 1.02 |
| A rolling boulder trap is invisible to clients | 1.02 |
| Constructs attached to a wall lose their attach state after loading | 1.02 |
| Cannot pick up coins or the fuse in some boxes | 1.01, again in 1.02 |
| Worse performance than expected from light invalidation | 1.01 |
| No public server browser | 1.07 — it did not exist before this |
Patch 1.06 also added “security measurements for incoming connection”, which is the kind of change that quietly resolves connection problems nobody filed a precise report for.
Things that are not bugs
Two of the most common “multiplayer is broken” reports are probably not faults. The first rests on player consensus, the second on an official patch note — different levels of certainty, so they are labelled differently below.
Missing rooms or a locked floor after joining someone
Community The player explanation is that progression follows the host: you are playing their Outpost, so their unlocks are what you see, and a host further behind will show you doors you had already opened. Say it plainly though — that is the likeliest explanation, not a confirmed rule, and the developers have never written it down. If you have ruled out being on a different save and it still looks wrong, it is still worth reporting. Decide whose save the group is pushing before the first run. Full explanation on the floor 2 page.
Not being able to find a public game before 12 August
The server browser arrived in 1.07. Before that, sessions were friends-only or invite-only by design, not by fault. What changed and how to use it.
Reports without an official fix
Honest gaps, all from the demo period, none matched to a patch note we could find:
Community A rescue quest failing after a death. One player’s account: “we found him, we brought him to the elevator, we got quest completed on our screen but then we died, and then the quest was failed” — with the NPC not respawning afterwards, forcing a fresh save. Reported 30 June, during the demo. We have not found a matching fix note, so if this happens on a current build it is worth reporting with your build number.
Community Cursor locked to the join-game button. A player described the mouse refusing to leave that UI region and bouncing back, needing a force-exit. Reported 5 July, demo period.
Community A fatal error on a specific save slot, reported 29 June by a player testing with Proton on and off. No replies, no fix note. Worth knowing if you are running through a compatibility layer, which is also relevant to the Steam Deck situation.
If you still need to report something
Include your build number and whether you were host or client. The fix list above is full of client-specific bugs — a door that opened for the host and not the client, a trap invisible to clients — so that one detail is often the whole diagnosis. The developers are shipping fixes at a pace that makes a good report genuinely worth writing.