A player for a modded minecraft server I am running is having trouble connecting. We have triple checked the Neoforge and modpack versions (ATM 10-4.4 and Neoforge 21.1.191) and she still cannot connect. We have tried rebooting and reinstalling everything we can think of. The only other oddity is that the server console is showing her as an active player, but I cannot kick her (Shows “No Player Found”).
Error in log :
[23Jul2025 01:34:43.007] [User Authenticator #2/INFO] [net.minecraft.server.network.ServerLoginPacketListenerImpl/]: UUID of player AntagonistSimp is 978ec089-d806-497b-ad68-5fe644c8f3d5
[23Jul2025 01:34:43.304] [Server thread/INFO] [net.minecraft.server.network.ServerConfigurationPacketListenerImpl/]: com.mojang.authlib.GameProfile@75ba039c[id=978ec089-d806-497b-ad68-5fe644c8f3d5,name=AntagonistSimp,properties={textures=[Property[name=textures, value=ewogICJ0aW1lc3RhbXAiIDogMTc1MzIzNDQ4MjgwMSwKICAicHJvZmlsZUlkIiA6ICI5NzhlYzA4OWQ4MDY0OTdiYWQ2ODVmZTY0NGM4ZjNkNSIsCiAgInByb2ZpbGVOYW1lIiA6ICJBbnRhZ29uaXN0U2ltcCIsCiAgInNpZ25hdHVyZVJlcXVpcmVkIiA6IHRydWUsCiAgInRleHR1cmVzIiA6IHsKICAgICJTS0lOIiA6IHsKICAgICAgInVybCIgOiAiaHR0cDovL3RleHR1cmVzLm1pbmVjcmFmdC5uZXQvdGV4dHVyZS8zMDc3NzU4MzRhOTRmZTU3MDgxOTI1MmNmM2NiYzY3ZjUyMzAwY2YzOWYwNTFhZmJjZGU5MGQ4N2FhMDJkM2VjIgogICAgfQogIH0KfQ==, signature=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]]}] lost connection: Incompatible client! Please use NeoForge 21.1.191
[23Jul2025 01:34:43.305] [Server thread/WARN] [net.minecraft.network.Connection/]: handleDisconnection() called twice
Reproduction Steps
Player downloaded fresh install of curseforge
Player downloaded matching modpack version
Player tried to join server with address others have successfully used
Player wasn’t able to join because of a Neoforge incompatibility
Even though you’ve triple-checked, the server is definitively reporting that the player’s client (AntagonistSimp) is not using NeoForge 21.1.191. The “No Player Found” when trying to kick is likely because the player never fully authenticated or joined the game world due to this incompatibility, even though their UUID was recognized during the login process.
The issue is almost certainly on the player’s side, specifically with their NeoForge installation or how the modpack is being launched.
Ask the player to send their Minecraft client logs. Search for line of the log that indicate the loaded NeoForge version. It should explicitly state something like NeoForge version: 21.1.191`. If it’s anything else, that’s the problem.