The developer of the "SEAMLESS CO-OP" mod for Elden Ring has restricted access to non-Steam versions starting with mod version 1.7.8. This causes a "steam datagram relay error" when attempting to open the world in-game. Additionally, downgrading the mod version and launching ersc_launcher.exe triggers a message: "This version of seamless co-op (1.X.X) is deprecated and requires an update," as the launcher checks the game and mod version through an Internet connection.
To bypass this issue without disconnecting your PC from the Internet, I created a .bat file that:
- Adds a firewall rule to block Internet access for
eldenring.exe. - Launches
ersc_launcher.exe. - Removes the firewall rule afterward to restore normal Internet access.
The script uses only Windows PowerShell for its operations.
Get the .bat file on the Releases page.
- Downgrade the mod to version 1.7.7 or below (compatible with DLC, starting from version 1.7.2).
- Install the mod as you normally would.
- Download the
.batfile from the Releases page. - Copy the
.batfile to your game root folder (the same location aseldenring.exe). - Run the
.batfile as Administrator. That's all!
- Download the
.batfile from the Releases page. - Copy the
.batfile to your game root folder (the same location aseldenring.exe). - Run the
.batfile as Administrator. That's all!
- This solution was created primarily for my own convenience and for a friend.
- I am not aware of a guaranteed method to use the latest version of the mod with a non-Steam version of the game, though options like the 'Online-fix' might exist. Feel free to explore that possibility if interested.
Disclaimer: Use this fix at your own discretion. Blocking and restoring Internet access via PowerShell scripts may have security implications; make sure you understand and are comfortable with the actions performed.