hi, I am using a few mods predominantly Bob/Angel and factorissmo2 along with squeak through, etc.
since 17.16 ( - 17.21) I am getting a desync on the second connection to the server, it can be the first player logging out and logging back in or a different player trying to login and I get the same result. I have debugged by removing plugins and testing and only one that fixes it is removing factorissmo2.

I have been researching how to debug this on discord + google & reddit for past few days but figuring out how to fix desync seems to be, find mod causing desync => remove mod => profit. which doesnt work here because removing this mod kills 80% of my factories.

The machine is a beefy dual E5 Xeon with 64 gigs of ram and a gigabit connect so keeping up with factorio shouldn't be an issue.

link to desync report: https://www.dropbox.com/s/cr9kgrd5rskrtrq/desync-report-2019-03-28_17-23-16.zip

Any help is appreciated. thank you.

Okay, I had a long hard look at that desync report, and I don't really know what to make of it. The entity IDs saved by Factorissimo differ massively between the two saves included in the report (which doesn't even make sense since most of them shouldn't ever be overwritten), pollution is different, fluid contents are different, and for some reason RSO also has large script data differences. I'm thinking that this may be some sort of vanilla bug, or also maybe not, but what I do know is that this bug can be better diagnosed by the Factorio devs than by me. So please report this on Factorio's bug report forum and see what they say. Please send me a link to the thread you make there so I can stay up to date.

thank you. link to desync report : https://forums.factorio.com/viewtopic.php?f=209&t=68679

• looking at recent threads, not sure devs actually check that section.

Yeah, that section may be low-priority since mods can cause desyncs simply by being written incorrectly, by no fault of the base game. On the other hand, from what I can tell the devs work on bugs one-by-one, and they move any reports they're working on into the "Assigned" section. The general bugs thread has similar levels of activity as the modded desyncs section.

I'll get back to this later and see if I can't find anything more interesting by checking out the saves ingame. Thanks for the patience.

Okay, that's a pretty base. I have some more questions for you. Did you change any mods or settings around the time the save started desyncing? How fast does this desync happen after the second player loads the game? Which Factorio versions did the server use?

some mods updated around that time. bobs mining, assembly etc. I didnt add any mods that I can recall.

Desync is almost instantaneous. player click connect -> it saves map on server -> player downloads map -> it tries to catch up -> it says saving map on server (again) -> get a desync report. the player never makes it into server.

this started at 17.16.

PS thank you for spending the time on this issue plus the mod in general, I really appreciate it :)

I'm out of ideas so far. Can you try to find a way to reliably reproduce the desync in as few steps as possible?

An important experiment you could conduct: Does your desync still happen if you disable every mod except Factorissimo?

just did multiple tests and angels refining forces the game to desync. without it, I have a working game but of course, there are no ores to work with anywhere on the map or in my factories...

with factorissmo2 + angel refining only, the server desyncs me but also crashes my client at the same time.