Th3Dilli Been getting an error since 1.21 where a user joins, has mods not allowed by the server, gets kick message saying "Server password protected or whitelisted".  It no longer advises people of mod mismatches.  I thought with time it'd resolve, but it hasn't and I am unsure if this is explicit to us.  

Naturally this is a big issue, if the players don't know which mods they're being kicked for or do not match versions, then they have no ability to amend it.  The only recourse is staff going into console and pulling the kick message, see below

25.5.2026 14:40:48 [Server Notification] Client 4 disconnected: Error using blocked mods: blocksoverlay (v4.9.0)
using mismatched Mods:
25.5.2026 14:40:48 [Server Notification] Last player disconnected, compacting large object heap...
25.5.2026 14:40:49 [Server Debug] Despawn player entity OwIing.
25.5.2026 14:40:49 [Server Event] Player OwIing got removed. Reason: uses mods not allowed on this server

Im using allow mode, if a player has a mod not from a whitelist, he will be kicked. I added to fairplay guardian config survival, game, creative built-in mods for both 1.22.1 and 1.22.2, so that players can play on different minor versions, but people with 1.22.1 are still being kicked. Can i fix this somehow? 

Hello, I am starting a new server and I am just trying to blacklist Block overlay. I am on your GitHub page trying to figure out these instructions, but in each example, you show the need to enter the mod's Hash #.
I have looked in the mod's JSON file and there is no Hash # listed. Also, when I google it tells me the hash can be found at the end of the site address, but that is not a number. It is xray. Is xray the hash?
I haven't actually installed it on my server yet. I wanted to wait and make sure i could get it working to minimize downtime.

One of the best mods, thank you 😀

I added this to my Server and over half of my Server mods stopped working 😅

we'er trying to get chisel wizard to work. its on the server but no one can use it unless its also on their client. even when the ckient matches the servers version the players get kicked. Edit "disablemismatch true" fixed it. A vieo on this mod would be helpful.

ItsCheif I have the same thing. It blocks other mods on the client even if they are not blacklisted.

I also changed the id in the archive of the mod that banned and Fair Play does not kick me. The mode is worth Allow, the mod is blacklisted

ItsCheif
that error looks like you are missing FPG on the server

v.1.21.5
Says here that I can use the default built in feature of "ModIdBlackList": [ "modid" ]," to blacklist mods without this mod, but I've tried this and it doesn't work. Neither the mod blacklist or whitelist features prevented me from joining my own server with the mods that aren't allowed.

Furthermore, while using this mod on 1.21.5 and running the command ".fpg add block blocksoverlay", it doesn't work. It just says "Argument 3 (addhash) is missing"

EDIT: Turns out the base game's mod blacklist feature only disables the mod on the clientside without denying the user entry to the server.
EDIT 2:
I have the mod set to block mode and edited the mod config file to block 1 single mod. When I join, regardless of whether I have the mod on or off, my game crashes with this errror:

System.Exception: Attempting to send data to a not connected channel. For optionally dependent network channels test if your channel is Connected before sending data.
   at Vintagestory.Client.NoObf.NetworkChannel.SendPacket[T](T message) in VintagestoryLib\Client\API\NetworkChannel.cs:line 85
   at FairPlayGuardian.FairPlayGuardianClient.b__8_0(EnumHandling& _) in /home/dilli/drive_linux/git_repos/vintagestory/mods/FairPlayGuardian/FairPlayGuardian/FairPlayGuardianClient.cs:line 51
   at Vintagestory.Client.NoObf.ClientEventAPI.TriggerIsPlayerReady() in VintagestoryLib\Client\API\ClientEventAPI.cs:line 428
   at Vintagestory.Client.NoObf.GeneralPacketHandler.HandlePlayerData(Packet_Server packet) in VintagestoryLib\Client\Systems\GeneralPacketHandler.cs:line 317
   at Vintagestory.Client.NoObf.ProcessPacketTask.ProcessPacket(Packet_Server packet) in VintagestoryLib\Client\Systems\ProcessPacketTask.cs:line 18
   at Vintagestory.Client.NoObf.ClientMain.ExecuteMainThreadTasks(Single deltaTime) in VintagestoryLib\Client\ClientMain.cs:line 786
   at Vintagestory.Client.GuiScreenConnectingToServer.RenderToDefaultFramebuffer(Single dt) in VintagestoryLib\Client\MainMenu\Screens\GuiScreenConnectingToServer.cs:line 298
   at Vintagestory.Client.ScreenManager.Render(Single dt) in VintagestoryLib\Client\ScreenManager.cs:line 760
   at Vintagestory.Client.ScreenManager.OnNewFrame(Single dt) in VintagestoryLib\Client\ScreenManager.cs:line 663
   at Vintagestory.Client.NoObf.ClientPlatformWindows.window_RenderFrame(FrameEventArgs e) in VintagestoryLib\Client\ClientPlatform\GameWindow.cs:line 112
   at OpenTK.Windowing.Desktop.GameWindow.Run()
   at Vintagestory.Client.ClientProgram.Start(ClientProgramArgs args, String[] rawArgs) in VintagestoryLib\Client\ClientProgram.cs:line 338
   at Vintagestory.Client.ClientProgram.<>c__DisplayClass10_0.<.ctor>b__1() in VintagestoryLib\Client\ClientProgram.cs:line 133
   at Vintagestory.ClientNative.CrashReporter.Start(ThreadStart start) in VintagestoryLib\Client\ClientPlatform\ClientNative\CrashReporter.cs:line 95

Allow mode dont work. Kick for server mods. As soon as I add the Xrey mod to the block through the config, I immediately get kicked from the server as in the picture

Th3Dilli Would you consider adding a player ignore list? That way we can use the username or UUID of a player to disable block/allow list checks fro that individual player.

When DisableMismatchCheck is false, players are kicked once for mismatch of the servers mods.
But when they rejoin they can play just fine without being kicked.

This mod is a genuine god send for large communities. I cannot thank you enough for making it and updating it. Awesome work.

Such a wonderful tool, I have much gratitude for this existing.

😒

I love this, thank you!

yeah

Does it works with current version? 

For a public server, this is a must have. Thank you for it!

Mohandar

This mod only check and verify's mods (so the client does not use unwanted mods) it does not do anything with downloading mods from moddb and will never

Th3Dilli
does it as well  force-downloads for those mods? (it would be so nice, where for example some mod have some trouble being downloaded by the vanilla game)

ValidUser

Well, if you join a server and your "client side business" has an impact on other players (on their potential resources, for example...), then yes, it's logic that admins should have the right not to allow it. Maybe try to think of others next time plz.

wXDogeKingXw

that is what the mod is for to restrict mods from the server side, you should be able to customize the configuration and then it should be able to detect mods that are unwanted and kick players for it if set to do so

Can you update to like, stop Xel Xray Mod?

Oh yay another nanny-net addition. What we do on the client-side is our buisness and NOONE EVER has the right to try and control that REGARDLESS of your intent. Major -respect for this one.

Ah I see, thanks for explanation. Sounds very handy then as an extra layer of server protection!

it can do integrity checks using hashes and it has more options to configure it
you can configure if you wanna accept additional mods or not in vanilla it always accepts additional you can just block specific ones

but if all you need is to block only a few specific mods then sure i would recommend you to use the inbuild feature

How is this different from the "Tweak: Added ability for server owners to blacklist client side mods. Add "ModIdBlackList": ["modid1","modid2"], to server config." added in rc-3/4?

\o/ Yep, thanks a lot!

Awesome dude ! Thanks