Backpacks keep vanishing.

[cyburnya]

Having an issue where several backpacks have begun to disappear. I can see the error message, which I've posted below, and can see the cached backpacks, but I don't actually know how to recover them.

Does this mod have any kind of way I can recover lost backpacks?

Below is the error. 1.12.2 forge.

[01:00:32] [Server thread/FATAL] [net.minecraft.server.MinecraftServer]: Error executing task java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Item was not a gui holder! at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_312] at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_312] at net.minecraft.util.Util.func_181617_a(SourceFile:47) [h.class:?] at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:723) [MinecraftServer.class:?] at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397) [nz.class:?] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_312] Caused by: java.lang.IllegalArgumentException: Item was not a gui holder! at com.cleanroommc.retrosophisticatedbackpacks.common.gui.PlayerInventoryGuiFactory.getGuiHolder(PlayerInventoryGuiFactory.kt:30) ~[PlayerInventoryGuiFactory.class:?] at com.cleanroommc.retrosophisticatedbackpacks.common.gui.PlayerInventoryGuiFactory.getGuiHolder(PlayerInventoryGuiFactory.kt:11) ~[PlayerInventoryGuiFactory.class:?] at com.cleanroommc.modularui.factory.AbstractUIFactory.createPanel(AbstractUIFactory.java:32) ~[AbstractUIFactory.class:?] at com.cleanroommc.modularui.factory.GuiManager.open(GuiManager.java:73) ~[GuiManager.class:?] at com.cleanroommc.retrosophisticatedbackpacks.common.gui.PlayerInventoryGuiFactory.open(PlayerInventoryGuiFactory.kt:26) ~[PlayerInventoryGuiFactory.class:?] at com.cleanroommc.retrosophisticatedbackpacks.network.C2SOpenBackpackPacket$Handler.onMessage$lambda$0(C2SOpenBackpackPacket.kt:36) ~[C2SOpenBackpackPacket$Handler.class:?] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_312] at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_312] at net.minecraft.util.Util.func_181617_a(SourceFile:46) ~[h.class:?] ... 5 more

[ChAoSUnItY]

Which modern UI version are you using?

[cyburnya]

Sorry for the delay. How would I find that out?

[ChAoSUnItY]

Go to mods folder to see which version you're using, if the mod jar's name is altered before, you'll have to look in mod list once in your minecraft main menu

[cyburnya]

modularui-2.5.0-rc4, looks like.