I am using the latest version of forge 1.16.5. My minecraft runs fine but when I make my single player world LAN and my sister tries to join she gets the error message "Failed To Synchronize Registry Data From Server". I know that my mods are up to date. Originally I was using the recommended version of forge but now I am using the latest version, we have the same problem with both versions. I tried deleting my sister's player data from the save, I tried using a backup of the save, I took many mods out of the folder as well. We played yesterday with no issues with the same mods so I don't know what the problem is. It worked once when she deleted all of her mods and re downloaded them but now I think that was random because she is getting the error message again.