we got this error.

The mod Quantum Fabrication (2.5.6) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event quantum-fabricator::qf-fabricator-gui-toggle (ID 219)
quantum-fabricator/scripts/gui/fabricator.lua:180: attempt to index field '?' (a nil value)
stack traceback:
quantum-fabricator/scripts/gui/fabricator.lua:180: in function 'build_main_recipe_gui'
quantum-fabricator/scripts/gui/fabricator.lua:48: in function 'build_main_gui'
quantum-fabricator/scripts/gui/gui_utils.lua:20: in function 'toggle_qf_gui'
quantum-fabricator/scripts/gui/events.lua:236: in function <quantum-fabricator/scripts/gui/events.lua:233>

experienced it when the 2nd player open up the fabricator GUI, who ever try to open up the GUI 2nd, it will not appear and crash the server, seems like the gui was exclusive to the first person who will open it up

Should be fixed now. The bug was a lot easier to fix than I initially imagined, the table I used for filtering just didn't updated properly in multiplayer.

thank you very much

Hi again, i just tested on a headless server earlier, when i open up the fabricator GUI, my client instantly desync. reconnecting to the server would show the fabricator GUI opened up then if i close and open it up again it desync again.

Well, that's a problem. I tested it with two clients running on the same PC and it worked fine.

I'll look into it, but no promises, I have no clue about multiplayer related stuff.

have you tried the headless server? our setup was 3 PCs, 1 headless factorio server, 1 for me and 1 for my friend.

Sorry, but I can neither reproduce nor locate the problem. I don't think the headless server would make the difference since desyncs can happen over LAN just as well.

Perhaps there is some weird interaction with another mod. Can you test if it still desyncs with just my mod active?

Sorry, but I can neither reproduce nor locate the problem. I don't think the headless server would make the difference since desyncs can happen over LAN just as well.

Perhaps there is some weird interaction with another mod. Can you test if it still desyncs with just my mod active?

no problem, we will try to test it by removing other mods.