MP dedicated server character data not saving | Project Zomboid | Page 1

hearty carbon Dec 23, 2025, 6:21 PM

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I suspect this might be mod related but if you have any tips on how I might better identify the responsible mod short of disabling one at a time I'd love to hear them... Long and short of it is sometime character data seems to not save right to the server and then when a server reset happens the character inventory/xp/status/etc get rolled back at least a few hours. Think the smoking gun is this error message which I saw when I logged out last night (and when I reset this morning progress was rolled back):

ERROR: Multiplayer f:204374, t:1766473303379, st:40,445,209,510> GameServer.main> Exception thrown
java.nio.BufferOverflowException at Buffer.nextPutIndex(null:-1). Message: Server error
Stack trace:
java.base/java.nio.Buffer.nextPutIndex(Unknown Source)
java.base/java.nio.HeapByteBuffer.putLong(Unknown Source)
zombie.characters.IsoPlayer.save(IsoPlayer.java:1409)
zombie.iso.IsoObject.save(IsoObject.java:1323)
zombie.savefile.ServerPlayerDB$NetworkCharacterData.<init>(ServerPlayerDB.java:49)
zombie.savefile.ServerPlayerDB.serverUpdateNetworkCharacter(ServerPlayerDB.java:179)
zombie.network.GameServer.disconnect(GameServer.java:3126)
zombie.network.GameServer$DelayedConnection.disconnect(GameServer.java:4272)
zombie.network.GameServer.main(GameServer.java:895).

I am running the following modlist https://steamcommunity.com/sharedfiles/filedetails/?id=3624049515 and while I suspect it's probably mod related I can't really tell what mod might be the culprit. The only other errors for hours prior to this are "IsoThumpable not found" which seem to be related to base building I was doing so I don't think those necessarily have to do anything with this. I haven't found a way to consistently replicate this error yet either so I haven't started trial and error with disabling mods.

hearty carbon Dec 23, 2025, 6:45 PM

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full log for reference (BufferOverflowException happens at line 36992)

📎 message.txt

azure cradle Dec 23, 2025, 6:54 PM

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Unfortunately, its just a buffer overflow error, which generally just means there is too much of something

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The data does point to players / character data. So possibly anything on the player such as items, clothing, skills, traits

hearty carbon Dec 23, 2025, 6:58 PM

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hmm i was using unlimited carry to rearrange our storage before that but i had redeposited everything i was carrying before logging out so i don't think it was too much in the inventory

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i am using the adaptive traits mod and from what i'm reading from forum posts from years back it sounds like traits mods are frequently at fault with this type of error? that's the only mod i'm running that is really directly interacting with player data

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unfortunately until i can find a way to reliably recreate this error i can't really confirm whether or not that mod is to blame

hearty carbon Dec 23, 2025, 7:21 PM

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also getting this error whenever i restart the server but it seems to occur after saving completes so i'm not sure if it's related:

LOG : General f:9102, t:1766517633275, st:40,489,539,405> Exception in thread "Thread-0" LOG : General f:9102, t:1766517633275, st:40,489,539,406> java.lang.NullPointerException: Cannot read the array length because "this.threads" is null

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just tried to recreate by triggering a trait loss with adaptive traits but i disconnected without the bufferoverflow, restarting to confirm whether or not it properly saved the lost trait

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yeah the trait dropped properly and character data saved that time, damn

hearty carbon Dec 23, 2025, 8:06 PM

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mod dev is saying others are reporting the same issue and is looking into it

hearty carbon Dec 23, 2025, 10:28 PM

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at least one person on IB discord reporting the same error with a vanilla server though, i'll update here if i find anything out

glossy kite Dec 29, 2025, 4:54 PM

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hearty carbon at least one person on IB discord reporting the same error with a vanilla server...

have you found out anything else

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im also suffering from this

hearty carbon Dec 29, 2025, 5:14 PM

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nope, we've just been making sure to drop gear and update skill journals before logging

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sometimes still get bit by crashes though

dire gazelle Dec 30, 2025, 8:24 AM

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hearty carbon also getting this error whenever i restart the server but it seems to occur afte...

There is a lot of null pointers errors, and I’ve seen the mod fixing it, yet not sure did I enable it or not for my server.

glossy kite Dec 30, 2025, 11:34 PM

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hearty carbon sometimes still get bit by crashes though

thats what bites me most currently

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i set my backup time to 4 minutes that has solved alot but not really

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i have also started closing and reopening the server hourly just about

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i guess opening the build menu after 3 hours of playtime is too much for the game 🤷‍♂️

#MP dedicated server character data not saving