Catherine Hu
Because Saber Interactive’s Swarm Engine utilizes cross-network backends to connect PC (Steam/Epic) with PS5 and Xbox players, the matchmaking architecture is incredibly complex.
In this comprehensive guide, we will break down exactly why your co-op connection is failing, how to fix your Epic Online Services (EOS) sync, and provide the hard technical fixes to get your squad connected.
You may also like: John Carpenter’s Toxic Commando cheat engine alternative
Editor’s Note: By Catherine Hu, Senior Editor at XMODhub.
As launch week servers stabilize, our technical team has discovered that the majority of “Failed to Join” errors are actually caused by silent PROS account desyncs and Crossplay version mismatches, rather than global server outages. Before changing your router’s DNS settings, verify that you and your friends have correctly linked your cross-platform accounts!
Quick Answer: 5 Steps to Fix Matchmaking Errors
(Can’t join your friend’s lobby? Run through this verified troubleshooting checklist to force a network handshake immediately.)
- Toggle Crossplay: Go to Settings > Network, turn Crossplay OFF, apply the settings, then turn it back ON to refresh your matchmaking token.
- Sync PROS Account: Ensure your Steam or Epic account is correctly linked to Saber’s PROS (Prism Ray Online Services) network via the main menu QR code.
- Match Game Versions: Verify that the host and all clients have the exact same game update installed. A 0.01 version difference will silently fail the matchmaking.
- Clear EOS Web Cache (PC): Press Win + R, type
%localappdata%\EpicGamesLauncher\Saved\, and delete thewebcachefolder to clear corrupted crossplay data. - Use In-Game Invite Codes: If Steam or Epic overlays are failing to send invites, use the game’s internal 6-digit lobby code system to join directly.
The Root Cause: PROS & Crossplay Architecture
Saber Interactive uses a hybrid matchmaking backend. To allow a Steam player, an Epic Games player, and a PS5 player to seamlessly join the same apocalyptic wasteland, the game relies heavily on Epic Online Services (EOS) and Saber’s proprietary PROS network.
If your local PC fails to authenticate with these third-party background services—due to a firewall block, an outdated launcher, or a corrupted web cache—the game cannot generate a valid session ID. This results in the Swarm Engine immediately aborting the connection to prevent a crash, displaying the generic “Matchmaking Not Working” prompt.
Fix 1: Epic Online Services & PROS Account Linking
If you are playing on Steam but trying to invite a friend who bought the game on the Epic Games Store, standard Steam invites will not work.
How to Fix Account Sync Issues:
- Boot up Toxic Commando and navigate to the Social/Multiplayer tab in the main menu.
- Look for the PROS Account Link prompt (often displayed with a QR code or a browser link).
- Follow the instructions to link your Steam/Epic profile to the central Saber network.
- Once both you and your friend have linked your accounts, restart the game. You will now be able to see each other in the cross-platform in-game friend list, bypassing the buggy storefront overlays.
Fix 2: The “Infinite Loading Screen” Matchmaking Bug
Sometimes, the matchmaking doesn’t say “Failed”; instead, it traps you in an infinite loading screen with the music looping endlessly after you accept an invite. This is usually a strict NAT type or firewall block preventing peer-to-peer (P2P) asset loading.
How to Allow the Game Through Windows Firewall:
- Press Windows Key + S and type Firewall & network protection.
- Haga clic en Allow an app through firewall > Change settings (requires Admin privileges).
- Scroll down until you find
ToxicCommando.exeyEOSOverlay.exe. - Ensure both the Private y Public checkboxes are ticked for both applications, then click OK.
Fix 3: Resolving Crossplay Version Mismatches
This is the #1 cause of silent matchmaking failures during launch week. PC storefronts (Steam/Epic) and Console networks (PSN/Xbox Live) push hotfixes at different speeds.
If Steam pushes Patch 1.02 on Tuesday, but Sony delays the PS5 certification until Wednesday, PC and PS5 players are on different versions. If you try to invite a PS5 friend from your PC, the game will fail without explaining why.
The Solution: Always check the bottom right corner of your main menu for the specific build number. Everyone in your squad must have the exact same string of numbers. If you are mismatched, you must wait for the platform networks to sync.
Fix 4: The “Mod Desync” Co-op Conflict
As the premier modding platform, XMODhub must address a critical technical reality: Your installed mods might be breaking your matchmaking.
- Visual Mods (Safe): If you are using our FOV Unlocker, 80s Cinematic ReShade, or Arcade Vehicle Handling, these are client-side only. You can safely matchmake in public lobbies without issues.
- Script Mods & Cheats (Causes Desync): If you have a script mod that changes weapon damage, or unlocks all perks, the server will detect a logic conflict between your client and the host’s vanilla client. The engine will instantly abort the connection.
The XMODhub Golden Rule:
If you want to use gameplay-altering trainers or heavy script mods in co-op, you MUST play in a Private, Password-Protected Lobby where the game’s telemetry is relaxed and all players agree to the modded ruleset.
Skip the Grind: Focus on Fun with the XMODhub Trainer
Once you have linked your PROS account, bypassed the firewall issues, and finally gathered your squad in a private lobby, why waste your limited gaming time grinding for Scrap?
If you want to skip the tedious resource farming and focus purely on the cinematic 80s carnage, you need our standalone desktop app.
How to Dominate in 5 Seconds:
-
Download and Launch XMODhub.
- Search John Carpenter’s Toxic Commando.
- Click “Play”.
- Use intuitive toggles to set Infinite Ammo, No Weapon Overheat, or Vehicle God Mode.
- Done. No attaching processes, no version matching, no crashing.
Our standalone app uses safe memory injection. When you use it as the host of a private co-op lobby, it operates completely flawlessly without triggering the matchmaking desync errors found in older, outdated cheat tables.
Conclusion: Assemble Your Squad
There is nothing worse than launch day matchmaking errors, but understanding how the Swarm Engine handles PROS, Epic Online Services, and local firewalls is half the battle. By clearing your web cache, utilizing internal lobby codes, and managing your mod loadouts correctly, you can bypass the “Matchmaking Not Working” screen permanently.
Keep this page bookmarked! As Saber Interactive releases official network stability patches after the March 12 launch, we will update this guide. Join the XMODhub Discord to find LFG (Looking For Group) channels and team up with other Commandos!
Secure your ultimate apocalypse squad:
Soy un jugador apasionado y escritor en XMODhub, dedicado a traerte las últimas noticias de juegos, consejos y puntos de vista.
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Nancy Miller