[0.12.26] Desync for one person, lag, crash to desktop

[tetryon]

Public modded dedicated 0.12.26 server.

I was logged on, as was IKCharlie. devilwarriors joined (who had been desyncing late last night) and soon after he joined, a desync with him happened. Server started to lag out/wasn't responding, and the response time in the upper right debug went to several hundred.

devilwarriors eventually dropped. Then the server dropped. I tried to reconnect, and couldn't.

I restarted the server.

It was slow to download the map - it hung at 0h remaining for a while. Then I had a message that IKCharlie was dropped (must have given up and killed his client).
After he dropped, I joined to a completely black screen with just the FPS in small letters in the *bottom right* (not top), then after a few seconds, crashed to desktop.

I restarted factorio, and made sure the server was started, then was shortly after able to connect to the server with no issues.

Unfortunately I don't have a save immediately before the crash, but I do have the latest autosave (maybe 20 mins old.. not sure). Crash log attached too.

[NoPantsMcDance]

Here is the desync reports. If you need anything else lemme know.

[kovarex]

Hello, there is a story to this bug.

We have multiplayer tests, that are also doing some random desyncs etc.
The tests were randomly crashing on this error from time to time, and no one had the time to look at it, and we kind of started to live with that, we thought that it is probably error of the test, not of the multiplayer logic.

But once I saw the exact same error in your log, I started to investigate, and I actually found some core errors in the multiplayer code, that could create problems in special cases.

Long story short, I fixed few problems, and our multiplayer tests are passing as stable as they never did (no error in 100 re runs), and this error should never happen again.

Fixed for 0.12.27

[tetryon]

Hello, there is a story to this bug.

We have multiplayer tests, that are also doing some random desyncs etc.
The tests were randomly crashing on this error from time to time, and no one had the time to look at it, and we kind of started to live with that, we thought that it is probably error of the test, not of the multiplayer logic.

But once I saw the exact same error in your log, I started to investigate, and I actually found some core errors in the multiplayer code, that could create problems in special cases.

Long story short, I fixed few problems, and our multiplayer tests are passing as stable as they never did (no error in 100 re runs), and this error should never happen again.

Fixed for 0.12.27

Well, I must admit, I do like a story with a happy ending. Glad to hear you were able to figure it out =)

[daniel_cps]

i'm always having desync errors and getting kicked out of my own hosted server - whereas my friend with his "not-so-good" pc is always ON and playing.

how do I force my Steam downloaded client to update to 0.12.27, or even, if I update the server to 0.12.27, will my client be forced to update - or will I be locked out due to version mismatch?

[sillyfly]

Enable beta updates for Factorio in Steam to get the latest experimental version (Keep in mind though that experimental versions, as the name suggests, may have bugs)