Stardew Valley Error Code stardew-mp: How to Fix Co-op Connection Issues

Medium 15-45 minutes Medium Severity Verified June 2026
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Error Code
stardew-mp
Brand
Popular Games
Product Type
game
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
15-45 minutes
The Stardew Valley stardew-mp error means the game cannot establish a connection between your client and the co-op host. This typically happens due to firewall restrictions, network configuration problems, outdated game versions, or Steam connectivity issues. The good news is that most causes are software or network related and can be resolved without any special hardware or technical expertise.
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Tools You'll Need

How to Fix Error Code stardew-mp

  1. Check That Both Players Are on the Same Game Version

  2. Restart Steam and Relaunch the Game

  3. Verify Steam Is Online and Not in Offline Mode

  4. Allow Stardew Valley Through Your Firewall

    Only grant firewall access to trusted applications. If you are on a work or school network, contact your network administrator instead of changing firewall settings yourself.

  5. Check Your Router and Enable UPnP or Forward the Required Port

    Router interfaces vary by manufacturer. If you are unsure about port forwarding, consult your router's manual or the manufacturer's support website.

  6. Have the Host Share a Direct Invite Code Instead of Using the Friends List

  7. Disable VPN or Proxy Services

  8. Verify Game File Integrity via Steam

  9. Check for Conflicting Mods (SMAPI Users)

    Back up your save files before making any changes to your mod setup. Save files are located in %AppData%\StardewValley\Saves on Windows.

  10. Test With a Different Network (Mobile Hotspot)

    Mobile data usage applies. Only use this step briefly to test connectivity, not for extended gameplay sessions.
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When to Call a Professional

If you have completed all steps above and still cannot connect, the issue may be at the ISP or network infrastructure level. Contact your Internet Service Provider and ask whether they block UDP peer-to-peer traffic or have CG-NAT (Carrier-Grade NAT) active on your connection — CG-NAT is a known blocker for Stardew Valley co-op. For console-specific issues (Nintendo Switch, PlayStation, Xbox), contact the platform's official support, as NAT type restrictions on consoles often require additional configuration through the platform's network settings menu. You can also reach Stardew Valley's developer support at ConcernedApe's official channels or the game's community forums on Reddit (r/StardewValley) for community-based help.

Frequently Asked Questions

Why does Stardew Valley say it cannot connect to host even though my friend is online?
Being online in Steam does not guarantee a direct network path between two players. The most common causes are mismatched game versions, a firewall blocking the game, a router with UPnP disabled, or an ISP using CG-NAT that prevents direct peer-to-peer connections. Work through the steps above starting with version matching and firewall settings.
What port does Stardew Valley use for multiplayer?
Stardew Valley primarily uses UDP port 24642 for its co-op multiplayer sessions. If you need to manually port forward to help the host accept incoming connections, forward UDP port 24642 to the host's local IP address on your router.
Can I play Stardew Valley co-op without Steam?
On PC, Stardew Valley multiplayer is built around Steam's networking infrastructure, so both players need active Steam accounts. However, you can also use a tool like Parsec or Steam Remote Play Together as an alternative method to share the game locally over the internet without relying on the native co-op system.
Do mods break Stardew Valley multiplayer?
Yes, mods can break co-op if not all players have the same mods installed, or if a specific mod is not multiplayer-compatible. If you use SMAPI, ensure both the host and joining player have identical mod lists and identical mod versions. When in doubt, test with all mods disabled first.
How do I join a Stardew Valley co-op game on the same WiFi network?
Even on the same local network, Stardew Valley routes its co-op connections through Steam. Make sure both players are logged into separate Steam accounts, both have the same game version, and Steam is online. Use the invite code method for the most reliable local connection. If local play still fails, temporarily disable any firewall or security software on both computers.

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