An Error Occurred Lethal Company Mods | Fix It Fast

You click Join, the screen loads, and the same popup kicks you back out. It’s irritating, since the message doesn’t say what failed. In practice, the popup often means the lobby handshake didn’t finish.

With mods, the most common cause is a mismatch: one player has a different game build, loader, mod version, or config. The fix is boring but reliable—get everyone on the same set, then test with a small profile.

An Error Occurred Lethal Company Mods

This section is a fast read on what to check first when you see the popup while running mods. Think of it as a sync problem until you prove it isn’t.

If you want the shortest path, use the table to pick a starting point, then follow the step blocks under it. Each block ends with a quick test so you don’t change five things at once.

What You See	Most Likely Cause	Fast Fix
Error popup right after Join	Host and client mod list differs	Import the same profile
Works vanilla, fails modded	Loader or mods out of date	Update loader and mods
Only one friend can’t join	One required mod is missing	Share a profile code
Crash or hang before menu	Bad plugin or corrupted files	Reset the profile cleanly

Confirm You Are Launching Modded

If you use Thunderstore Mod Manager or r2modman, launch from the manager’s Start modded button. Starting from Steam usually runs vanilla, which can create a mismatch without you noticing.

• Open your mod manager — Pick the profile you plan to use, then click Start modded.
• Check which profile is active — Profiles can look similar, so read the name twice.
• Try one join — If it connects, your base loader is working.

Run A Small Mod Set Test

A huge pack hides the culprit. A small test profile makes the problem show itself.

1. Create a fresh profile — Name it “Test” so you don’t mix it up.
2. Install only the loader — For most setups that’s BepInExPack.
3. Join a lobby — If it works, add mods back in batches.
4. Add mods in groups — When the popup returns, the last group contains the conflict.

Grab The One File That Makes This Easier

When a join fails, your best clue is the mod loader log. It can show a missing dependency, a plugin load failure, or a mod that threw an error on startup.

• Find the BepInEx folder — In most installs it sits in the game directory created by the loader.
• Open the log file — Look for lines that say a plugin failed to load or a dependency is missing.

Fix An Error Occurred With Lethal Company Mods After Patches

A patch can break modded multiplayer in a snap. The base game changes, then older plugins try to hook the wrong parts of the code. You can still reach the menu, yet joining a lobby fails with the popup.

The reliable path is to update in layers: game first, loader second, mods third. After that, test with a small pack so you can see what actually changed.

Update The Game In Steam

• Update Lethal Company — Let Steam finish downloads and file writes before you launch again.
• Launch vanilla once — Confirm the game can reach the menu with no mods loaded.

Update BepInExPack In The Same Profile You Play

If your profile points at an older loader, every mod in that profile sits on shaky ground. Update the loader first so the folder structure and core hooks are current.

1. Open your mod manager — Select the profile you use for multiplayer.
2. Check for updates — Update BepInExPack inside that profile.
3. Start modded once — Let the loader rebuild folders and write fresh logs.

Update Mods In One Pass, Not One At A Time

Update everything in the profile in one sweep so versions stay aligned.

• Sort by update available — Apply all updates, then restart the manager.
• Update shared libraries — Libraries matter even when they look “invisible.”

Disable Mods That Touch Lobbies, Then Add Them Back

Some mods change lobbies, syncing, or player data. Those mods often need perfect version matches across everyone in the lobby.

1. Disable lobby and matchmaking mods — Start modded and try one join.
2. Disable overhaul-style mods — Big gameplay changes can ship networking hooks.
3. Re-enable mods one group at a time — Stop once the join fails, then focus on that group.

If you want a quick sanity check, read this phrase exactly as written once: an error occurred lethal company mods. Treat it as a sync warning, not as a mystery. You’ll fix it faster by lining up versions than by hunting random settings.

Make Your Mod List Match The Host

In co-op, “works for me” isn’t a useful clue. Joining is a shared act, so your setup has to match the host’s setup. When one player has one extra plugin, or a different version of the same plugin, the game can reject the connection with that generic popup.

Take the human error out of the loop. Use a shared profile or a shared modpack so everyone pulls the same mods and the same versions in one step.

Share A Profile Code Instead Of Listing Mods In Chat

Thunderstore Mod Manager and r2modman can export a profile code. It’s the fastest way to line up a group, since the import pulls each package and its dependencies.

1. Export your profile — In the profile menu, choose the share or export option.
2. Send the code — Have friends import the code into a new profile with a clear name.
3. Start modded from that profile — Everyone should launch from the manager, not from Steam.

Sync Config Files When A Mod Uses Them

Some mods store settings in config files. A join can fail when one person changed a setting that affects lobby data or sync rules, even when the mod versions match.

• Open the profile folder — Most managers have a button to browse it.
• Copy the config directory — Zip the folder so you don’t miss hidden files.
• Replace configs on each PC — Do it with the game closed, then start modded again.

Check For Mods That Require Everyone To Install Them

Some mods are harmless client-side changes. Others need every player to run the same mod, often the same exact version. If a mod’s page mentions that all players must use it, treat it as non-negotiable for your pack.

Reset Mods Cleanly Without Losing Your Game

If updates and syncing don’t fix it, treat the install as corrupted. A clean reset is often faster than endless toggling, and it clears broken DLLs and half-updated plugins that sit in the wrong folder.

This reset targets the mod loader files and profile folders. Your Steam saves are handled separately, so the game itself stays intact.

Back Up The Parts You Actually Care About

• Export the profile code — This preserves your mod list and versions.
• Copy your config folder — Keep it in a safe place so you can restore settings later.

Reset The Profile When You Use A Mod Manager

If you installed through a manager, reset by deleting the profile, recreating it, then importing your profile code.

1. Close the game — Also close the mod manager so no files are locked.
2. Delete the broken profile — Create a new profile with a clear name like “Fresh.”
3. Install BepInExPack only — Start modded once and reach the menu.
4. Import your mod list — Add your full pack back from the profile code.

Bring The Pack Back In Batches

Once the loader is clean, rebuild your pack in groups. Start with libraries, then core gameplay mods, then cosmetic changes. Test multiplayer after each group so the breaking change is always close to the last thing you touched.

• Add libraries first — Shared dependencies should load cleanly before anything else.
• Add your must-have gameplay mods — Keep the first batch small and test joining.

Keep a known-good profile so you can roll back fast when a new update breaks multiplayer.

Fix Loader And File Path Problems

Sometimes the popup isn’t a mod conflict at all. Your manager may be launching the game from the wrong folder, or Steam libraries may confuse the path scan. That can lead to a “modded” launch that isn’t fully modded.

These checks focus on the launcher side: where the game is installed, how it starts, and whether the loader can write logs and config files.

Use The Manager’s Launch Button Every Time

• Click Start modded — Use the same profile each time you play.
• Remove Steam launch options — Extra flags can change how the game boots.
• Confirm mods loaded — Check for a BepInEx console window or a loader log after launch.

Fix Steam Library Detection Issues

If the manager can’t find Lethal Company, it may point at the wrong Steam library. Re-scan libraries, then select the correct install location for the game.

1. Open manager settings — Look for Steam directory or game path fields.
2. Re-scan your Steam libraries — Let the manager rebuild its game list.
3. Select the correct folder — It should be the folder that contains the game executable.

Check Permissions And Security Tools

If the loader can’t write files, mods may fail to load cleanly. That can leave you with a join error that looks like a network issue.

• Allow the install folder — Antivirus tools sometimes quarantine DLL files.
• Check the loader log — Look for “failed to load” lines right after startup.

When It Is Not Mods

This popup can show up in vanilla too. Before you dig through plugins, do one vanilla join test.

• Verify game files — In Steam, use Verify integrity so missing files get replaced.
• Restart Steam and your PC — A fresh session clears stuck sign-ins and cached lobby data.

Quick Checklist Before You Hit Join

Run this list in order, then test after each step.

1. Try vanilla once — If vanilla fails, fix Steam or your connection first.
2. Start modded from the manager — Use the correct profile every time.
3. Update the loader and mods — Update everything in the active profile in one pass.
4. Import the host’s profile code — Don’t hand-match mods by memory.
5. Test with a small pack — Loader only, then add mods in groups.

If the popup keeps coming back, open the loader log from a fresh launch and remove the first mod that fails to load. In most cases, an error occurred lethal company mods is a sync problem you can solve on your side by lining up versions and configs.