Factorio Forums

Hi, me and my friend have been playing this new map for about 10 hours, and we're not sure why, but lately we have constant desync issues. It's increased if we build/do something but it regulary happens every 5-10sec. It doesnt matter who is hosting , it happens to the other player.

The log is https://www.dropbox.com/s/3ynb7cn1nbt5w ... txt?dl=0[1]
And where the desync happens is:

053.727 Error NetworkInputHandler.cpp:341: Multiplayer desynchronisation: crc test(CheckCRCHeuristic) failed for mapTick(4691640) peer(1) testCrc(-1471410444) testCrcPeerID(0) currentCrc(-1713401259)
7053.727 Info NetworkInputHandler.cpp:417: Desync specification: Reference CRC = 2823556852, reference peers = {0 (isildria)}; desynced CRC = 2581566037, desynced peers = {1 (valerate)}

The save is here: https://www.dropbox.com/s/h8fk45ps9zvzq ... 3.zip?dl=0

Ok, but I would also need the mod folder to be try to simulate the problem.

I have downloaded the mods and managed to reproduce the issue.

The desync is caused by Treefarm-Lite ... but I am not sure why. The farms use fertilizers in different ticks, but the mod seems to serialize everything to save correctly. I suspect some rounding error, but I need to investigate more.

So after more investigation we were able to confirm rounding errors in float point computation was cause of the desync in Treefarm-Lite. Rseding suggested increasing precision of floating point values in serialized Lua tables in save files, so we tried it and it seems to fix the issue. So this is fixed for next release.