Describe the bug
I opened this under iron431/irons-spells-n-spellbooks#537 but they blame SophisticatedBackpacks.

Upgraded ATM10 server to 0.33 today. Made a Sophisticated backpack, put it in curio back slot. After 1 or 2 openings, the client crashes. If I remove backpack from curios slot it works fine. If I remove all iron rings and necklace from curios backpack works fine from curios slot.

Client disconnected with reason: Failed to open a screen with advanced data: java.lang.ClassCastException: class io.redspace.ironsspellbooks.item.curios.CurioBaseItem cannot be cast to class net.p3pp3rf1y.sophisticatedbackpacks.backpack.BackpackItem (io.redspace.ironsspellbooks.item.curios.CurioBaseItem is in module [email protected] of loader 'TRANSFORMER' @3be3e76c; net.p3pp3rf1y.sophisticatedbackpacks.backpack.BackpackItem is in module [email protected] of loader 'TRANSFORMER' @3be3e76c)

Crash log if it's a crash.

Info on what other mods you're using that may cause a conflict here if applicable.
ATM10 0.33, no additional mods

Please go to Discussions to add new feature requests / suggestions or comment on existing ones.

To Reproduce
Steps to reproduce the behavior:

1. Have iron poison and fire ring, and a necklace in curios.
2. Put sophisticated netherite backpack in curios.
3. open backpack with hotkey, crash

Expected behavior
No crash :)

Screenshots
If applicable, add screenshots to help explain your problem.

Versions
Neoforge 21.1.8
sophisticatedbackpacks-1.21-3.20.6.1055
irons_spellbooks-1.21-3.4.4-all

The crash happens because on server there's backpack in the slot, but on client it isn't in that same slot for some reason???
I am unable to recreate when testing on dedicated server, the only guess I have is that you have different configs between server and client and the curios mod isn't able to reconcile that for some reason?

Anyway I will need exact steps how I can recreate otherwise I am not able to do anything here.

Let me get my server admin to verify the config between client and server for curios.

The way we typically play is to add as many curios slots as we need, to be able to equip found items.
/curios add ring @s 10
etc.

Changing the setting on the server seems to have fixed the issue. Thanks again!