ICARUS Server Troubleshooting
ICARUS tickets land in our queue most weeks, and nine times out of ten it's one of the same handful of problems. This guide walks through what we actually see on support, in roughly the order we check things ourselves. If you haven't set the server up yet, start with the ICARUS Getting Started Guide and the Server Settings Guide instead.
A quick orientation: your live panel is TCAdmin at control.low.ms. When we mention sidebar items like Log Viewer, Web Console, Configuration Files, Steam Update, Backup Manager or File Manager, that's where to find them. Your ServerSettings.ini lives at Icarus/Saved/Config/WindowsServer/ServerSettings.ini and is editable directly from Configuration Files.
The server shuts itself down after a few minutes
This is the single most common ICARUS ticket we get. The server boots, runs for five minutes, then quietly stops. People reach for the panic button, but the cause is almost always two innocent-looking settings.
ShutdownIfNotJoinedFor and ShutdownIfEmptyFor both default to 300 seconds. The trap: setting them to 0 does not disable the timer. It tells the server to shut down immediately. We've seen plenty of operators copy that advice from old forum threads and then wonder why their server dies the second it boots.
What you actually want is a very large value. We recommend 24 hours:
ShutdownIfNotJoinedFor=86400
ShutdownIfEmptyFor=86400
A few operators report -1 works as a true disable, but it isn't in any official documentation we trust, so we'd stick with the high-number approach.
Players can't connect to the server
Connection failures are the second-biggest category. Before you start tearing the config apart, work through these in order.
First, check the version. After an ICARUS patch the server and every client must be on the same build, and a mismatch produces a generic timeout with no helpful error. In TCAdmin, hit Steam Update to force the server onto the latest build, then have your players verify their game files in Steam.
Second, make sure there's actually a prospect loaded. ICARUS will happily run a dedicated server with no prospect attached, and clients trying to join will just bounce. Your ServerSettings.ini needs one of:
ResumeProspect=Truetogether with a validLastProspectNameLoadProspect=MyBaseto load a specific saved prospectCreateProspect=Olympus_Outpost 3 false MyBaseto spin up a fresh one
That CreateProspect syntax trips people up. It's space-separated, not colon-separated: prospect type, difficulty (1-4), hardcore flag, then the save name. The map is implicit in the prospect type.
Third, check JoinPassword. Obvious, but we've closed enough tickets on this one to mention it.
Finally, give the server time. ICARUS can take a few minutes to fully initialise on first boot, especially with a large existing prospect. Watch Web Console and wait until it reports ready before you start blaming the network.
The server doesn't show up in the in-game browser
ICARUS uses UDP 17777 for the game itself and UDP 27015 for the Steam query port. If 27015 isn't reachable, the browser entry never appears even though the server is perfectly healthy. On a shared IP your assigned ports may not be the defaults, so always grab the real ones from your service page in TCAdmin.
Two practical notes. The Steam master server list can take five to ten minutes to refresh after a restart, so don't panic if your server is briefly invisible. And if you just need players in right now, Direct Connect by IP and port works fine and bypasses the browser entirely.
One other quirk worth knowing: the in-game SessionName setting is currently broken upstream. If you want a custom name in the browser, set it via the command line with -SteamServerName="Your Name Here" instead. We add this to the launch arguments for customers when they ask.
Joins time out on the loading screen
Players click join, the loading screen appears, then they get bounced back to the menu. This is almost always prospect load time exceeding the client's connection timeout. Open World saves with a lot of player building can be enormous, and ICARUS has to stream all of it before the join completes.
A few things help. Have players install ICARUS on an SSD if they aren't already; client-side load time is a real factor here. On the server, pruning genuinely abandoned bases or splitting a sprawling Open World into a fresh prospect makes a noticeable difference. If your plan has headroom, more RAM lets the server keep more of the prospect resident instead of paging.
Lag, rubberbanding and general performance
ICARUS is built on Unreal Engine 4, and like a lot of UE4 games it leans heavily on a single thread for the main game loop. AI, weather, and player interactions all share that thread, so performance tends to fall off when several players are spread across the map, when a storm rolls in, or when someone has built a contraption with hundreds of moving parts.
There isn't a magic fix for this; it's the nature of the engine. What we'd actually try first:
- Schedule a nightly restart from TCAdmin during off-peak hours. Long-running ICARUS processes accumulate memory and a clean restart helps more than you'd expect.
- Check Log Viewer for repeated warnings or errors. A misbehaving mod or a stuck AI pack can saturate the loop on its own.
- If only one player is laggy, it's probably their connection. Wired Ethernet, lower view distance, and a Steam file integrity check fix this more often than not.
For server-side resource sizing, our ICARUS hosting page has the current options.
Corrupt prospect files
If your server refuses to start and the logs mention a missing or unreadable prospect, the save itself has likely been damaged. We see this most often after a hard crash mid-save.
Your first move is Backup Manager: pick the most recent Cloud Backup from before the crash and use Cloud Restore. We run automatic cloud backups on every ICARUS plan, so there's almost always something to roll back to.
If you're starting fresh instead, open File Manager, navigate to Saved/PlayerData/DedicatedServer/Prospects/, and move the bad .prospect file out of the way (don't just delete it; you may want it for support). Then point ServerSettings.ini at a new prospect with ResumeProspect=False and a CreateProspect= line.
A habit worth building: take a manual backup before every game update. ICARUS patches occasionally change save format, and a pre-update snapshot has saved more than one community for us.
DLC mismatches
ICARUS has Olympus as the free base map, plus Styx, Prometheus (New Frontiers) and Elysium (Dangerous Horizons, released March 2026). To join a prospect on a paid map, players generally need to own that DLC themselves. If half your group can see the server but can't actually load in, check who owns what before you go any further. The simplest fix is to keep an Olympus prospect handy for mixed groups.
Mod crashes
ICARUS mods are .pak files that live in Icarus/Content/Paks/mods/ and come from Nexus Mods (there's no Steam Workshop integration for ICARUS). When a server crashes shortly after boot and mods are involved, the fastest path to a culprit is binary search:
- In File Manager, move every
.pakout of the mods folder. - Restart and confirm the server is stable bare.
- Add mods back one at a time, restarting between each, until the crash returns.
The mod that breaks things is usually one that hasn't been updated for the current ICARUS build. Every connecting player needs the same set of mods installed locally, so make sure your group is in sync once you've found a working combination.
Lost characters and progress
This one isn't always a bug. Mission prospects in ICARUS are time-limited, and if you don't extract before the dropship leaves, you lose whatever you brought down with you. That's by design, and we can't restore it.
For Open World and Outpost prospects, real progress loss usually points at a crash mid-session or a restore from an older backup. Check Log Viewer around the time the player noticed, and if there's a crash in there, restore the most recent good Cloud Backup from Backup Manager. If the player insists their progress vanished without any server-side event, it's worth checking whether they accidentally joined a different prospect; we've seen that one too.
If you've worked through all of this and you're still stuck, open a ticket from your TCAdmin account and we'll dig into your specific server.