An Error Occurred Lethal Company | Fix It In Minutes

You click Join, the lobby looks open, then the game throws the same line again — an error occurred. It’s one of those problems that feels random until you sort it into buckets.

This guide walks you through fixes that solve the issue on Windows. You’ll start with quick checks, then move to deeper repairs, and finish with the signs that tell you the problem is outside your PC.

What The “An Error Occurred” Message Usually Means

Lethal Company uses Steam for matchmaking. That means the message can come from three places. A Steam session may not handshake, your local game files may be off, or a modded setup may not match what the lobby expects.

The trick is to read the pattern, not the vibe. A few clues narrow it down fast.

• Only fails on public lobbies — Steam matchmaking, region routing, or the lobby is already in a weird state.
• Works when you host — joining is the issue, not running the game.
• Fails only with mods — one plugin is outdated, missing, or conflicts with the host’s setup.
• Fails after an update — your files, mods, or loader didn’t update cleanly.

Before you change a bunch of settings, get one clean baseline. Run the game once without mods, without overlays, and after a quick file check. If vanilla works, you’ve already narrowed the hunt.

An Error Occurred Lethal Company Fast Triage Checklist

If you want the shortest path, follow the order below. Each step is quick, and each one rules out a common cause.

Step	When To Try It	What It Tells You
Relaunch Steam and the game	First try	Clears stuck session tokens
Join by invite or host a lobby	Public join keeps failing	Separates join issues from run issues
Verify integrity in Steam	After updates or crashes	Repairs missing or changed files
Launch vanilla with no mods	You use BepInEx or a mod manager	Confirms mod mismatch vs network
Reset network basics	Friends can join, you can’t	Targets DNS, proxy, firewall blocks

• Restart Steam — Exit Steam, wait ten seconds, then open it again before launching the game.
• Restart the game — Quit to desktop, not just the menu, then relaunch and try a different lobby.
• Try an invite path — Have a friend invite you from their lobby, or host and invite them back.
• Verify game files — In Steam, open Properties, then Installed Files, then run Verify integrity.
• Test a clean vanilla run — Disable your mod loader and confirm you can join at least one lobby.

If the error vanishes after the vanilla test, skip the network section and go straight to the mod mismatch section. If vanilla still fails, keep going in order.

Fix Mod And Plugin Mismatches First

Mods are a top trigger for this error because multiplayer often expects matching code paths. A lobby can reject you if the host runs a mod you don’t have, if you run a plugin they don’t, or if one of you has a different version.

Start by proving your base game works. Then bring mods back in a controlled way.

Do A Clean Vanilla Launch

Close the game, then disable your mod loader for one run. If you use Thunderstore, switch to a profile with no mods or use the vanilla launch option. If you installed BepInEx manually, move the BepInEx folder and related files out of the game directory for a moment.

• Launch without mods — Start Lethal Company from Steam and join a lobby to confirm the base game is fine.
• Bring mods back slowly — Enable a small set, test, then expand until the error returns.
• Match the host exactly — Copy the same mod list and versions between players, not just the mod names.

Clean Up BepInEx Leftovers

When BepInEx updates or a plugin fails, extra files can stick around and break launches or joins. A “clean reinstall” means removing the loader files, not just disabling mods in a manager.

• Remove the loader folders — Delete the BepInEx folder and any doorstop or winhttp files the loader added.
• Reinstall the right build — Use the version that matches the game’s Unity build and your system architecture.
• Update plugins together — If you play with friends, update everyone’s plugins in the same session.

Watch For “Must Match” Mods

Some mods are client-only, while others change gameplay logic. Anything that changes enemy behavior, loot rules, or lobby behavior can require everyone to match. If you see the error only when joining specific lobbies, odds are the host runs a mod set you don’t share.

• Ask for the mod code — If your group shares a Thunderstore code, import that code instead of guessing.
• Avoid mixed installs — Don’t combine manual BepInEx installs with a manager profile for the same game.
• Disable extra overlays — Overlays from capture tools can collide with mod loaders, so test with them off.

Once your modded setup is stable, try joining again. If you still get an error, move to Steam and file repairs next.

Repair Your Steam Install And Game Files

When the game files don’t match what Steam expects, multiplayer can fail in weird ways. A file check is quick, and it fixes more than people think.

Verify Integrity The Right Way

In Steam, open your Library, right-click the game, then open Properties. Under Installed Files, run Verify integrity. Steam will re-download missing files and replace changed ones.

• Wait for completion — Let Steam finish the scan and any downloads before launching.
• Reboot after repairs — A restart clears file locks and stale background hooks.
• Test joining first — Try joining a lobby before you reinstall anything else.

Clear Steam Download Cache

If updates keep acting odd, your download cache can be part of the mess. Clearing it signs you out, so have your login ready.

• Clear the cache — In Steam settings, find Downloads, then choose Clear Download Cache.
• Sign back in — Log in again, then check for a pending game update.
• Retry matchmaking — Launch the game and try a couple of different lobbies.

Do A True Clean Reinstall When Needed

If verify doesn’t fix it and you have a long mod history, a clean reinstall can help. Uninstalling alone may leave extra files behind in the game folder.

• Uninstall in Steam — Remove the game from your Library.
• Delete leftover files — Open the install directory and remove any remaining Lethal Company folder.
• Install fresh — Reinstall, then launch vanilla once before adding anything else.

If you still can’t join after a clean reinstall, you’re likely dealing with network blocks, proxy settings, or a Steam-side hiccup.

Reset Connection And Windows Network Settings Safely

Network fixes are boring, yet they work. You’re trying to remove the quiet blockers, like a flaky DNS route, a proxy flag, or a firewall rule that doesn’t like the handshake.

Start With The Simple Stuff

Make one change at a time so you know what solved it. If you change five things at once, you won’t know what to repeat later.

• Restart your router — Power it off for thirty seconds, then let it fully come back online.
• Use a wired link — If possible, test with Ethernet to rule out Wi-Fi drops.
• Stop VPN or proxy apps — Turn them off for a test run, then try joining again.

Check Windows Proxy Settings

Windows can auto-detect a proxy and route traffic in a way that breaks some games. Turn it off for a quick test.

• Open Proxy settings — In Windows Settings, go to Network and internet, then Proxy.
• Turn off auto detect — Disable Automatically detect settings, then retry the game.
• Remove manual proxies — If a manual proxy is set, disable it unless you truly need it.

Flush DNS And Reset Winsock

If your connection is stable but matchmaking fails, flushing DNS and resetting Winsock can clear stale routes.

• Flush DNS — Open Command Prompt as admin and run ipconfig /flushdns.
• Reset Winsock — Run netsh winsock reset, then restart your PC.
• Retry with Steam open — Launch Steam first, then the game, then try joining.

Allow The Game Through Firewall

Firewalls can block inbound and outbound connections in ways that show up as a plain error message. If you use a third-party firewall, test by disabling it for a minute, then re-enable and set a rule instead.

• Check allowed apps — In Windows Security, open Firewall and network protection, then allow the game and Steam.
• Disable extra filters — Some antivirus web filters can block game traffic; pause them only for a test.
• Keep one firewall active — Don’t run two firewall layers at once.

At this point, your PC should be clean, your files should match Steam, and your connection should be direct. If the error still hits, it’s time to check whether the issue sits on the service side.

When It’s On Steam Or The Game Side

Sometimes you do everything right and the error still pops. That happens when Steam services wobble, matchmaking routes are overloaded, or a patch lands and breaks joining for a slice of players.

Spot The Service Pattern

Service-side trouble tends to show up as waves. You’ll see lobbies fail back to back, your friends report the same, or Steam itself throws web errors in the client. If Steam pages fail to load or friends can’t invite, pause and retry.

• Check Steam status — If Steam is having issues, wait and retry later.
• Try hosting — Hosting can work even when joining is flaky.
• Join smaller lobbies — Busy sessions can desync fast; pick a lobby with open slots.

Use A Clean Run Checklist

When you want to stop tinkering and just play, run this tight loop. It’s the fastest way to get back into a lobby without guessing.

1. Close the game — Exit to desktop, then wait five seconds.
2. Exit Steam — Quit Steam from the tray and reopen it.
3. Launch vanilla — Start with no mods and no overlays.
4. Join by invite — Use a friend invite path once, then try public lobbies.
5. Re-add mods later — If vanilla works, rebuild your mod list in small steps.

If you keep seeing an error occurred lethal company after all of that, log the pattern you see. Does hosting work, do invites work, does it fail only with one friend, does it fail only with mods. That pattern is your map.

One last note. If the message started right after a Steam outage, don’t burn an hour reinstalling. Test again after Steam services settle, then return to this list if the problem sticks.

If you came here searching for an error occurred lethal company because you can’t join any lobby at all, the clean baseline plus file verification fixes it most of the time. When it doesn’t, the mod mismatch steps and the proxy and firewall checks are the next best bets.