Desync After Joining A Zwifter (Teleporting) Between Players [1.67] [June 2024]


Recently the community of people I use Zwift with have noticed a potentially new bug. We stream and ride together often. We have noticed a new issue where after teleporting to ride with a friend, what we each see happening on screen is out of sync.

As an example, I was cycling with a friend recently trying to do a vEverest attempt, during the ride I was seeing myself ahead of the other player, and he was seeing himself ahead of me. Multiple people in our community have noticed this recently. It is not an issue that we have previously encountered.

Please validate if this is seen internally also.

Yeah, I noticed this issue as well. At one point, the desync created a 40 meter discrepancy (about 10 seconds at our pace up radio tower) between me and the other person.

Maybe this is related to a recently added feature which you can notice in Zwift log, “Donut Fail-Safe V2”. Check your log for messages like Donut fail-safe for player xxx took xxx ms | Distance increased. Apparently now it can take longer to sync riders.

It seems to be happening most noticeably during teleporting to other riders and/or U-turns for hill repeats. Would be tragic for any competitive sprints/race finishes.

If Zwift is able to reproduce the issue internally, they should be able to indentify the cause and fix, without our need to troubleshoot the problem. This is interesting though.

Shuji at Zwift HQ. Thanks for flagging this up everyone.

Questions for added context:

  1. When did you start noticing this behavior?
  2. Very important: did all of you do a U-turn or teleport? Or did you stay on the route you started when it happened?

FWIW, all of you were using game version 1.67 and Windows machines during your last session, so we can rule out game version 1.68 as a factor

I started noticing this desync issue yesterday during a friend’s veverest attempt. When comparing both our livestreams, it appears that the desync didn’t happen immediately after the warp, but instead happened after a rep of radio tower. We U-turned at the top, then again at the bottom. It was at this point that the game desynched us. When comparing VODs, I was now 10m off from my friend. This gap continued to grow during this next rep until about 28-30m and we would only resync at the top when we U-turned to go back down the hill. You can even see some level of rider ‘teleporting’ upon execution of the U-turn.

My experince was similar to what @Aaron_Pookie is describing. It was during a seperate vEverest attempt up the grade however. I am on the latest build of Windows 10 currently. I am not sure the exact Zwift version at the time, it would have been a week or two ago. I think the bug should be reproducable in Zwifts lab using two Windows clients.

I decided to report this because when it happened to me I thought it was an isolated occurence, and I chopped it up lag, or something else. However then other people in our community started reporting the same behaviour.

My teammates and I are struggling with this one on the WTRL TTT’s starting in June as well.
Oddly, not all of them (rather, they see those of us experiencing the issues, but don’t seem to have it themselves), but one other in particular as well, who I do know is on Windows. As for the others not seeing these desyncs, I’ll have to ask them tomorrow.

For me I’d be hanging out the back like 10-20m, while on my screen I’m the one pulling… and other times, I’ll be pulling and they might see it, but I’m not providing any draft somehow?

Things ebb and flow in terms of syncing, but it’s as broken as much as it’s not broken, and for the TTTs… well, simply put… makes them not possible (and understandably not enjoyable one bit) when you don’t have accurate positions of your teammates.

Something with the netcode has absolutely been screwed with this month.

I have not received the new update as of yet, but, definitely want to agree that it started to appear after 1.67

Interesting, no one in our group has had the issue while doing a TTT. That doesn’t mean it couldn’t be happening though.

Thanks for the added context everyone.

We think we’re on the right track to fixing the positional discrepancy. I’ll update as we get closer to an ETA.

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Happy to share all of my logs if it’s helpful lol! I’ve got plenty now :laughing:

Was still happening today after getting this week’s 1.68 update.

I will also state that starting … Monday I think? the “connection disconnected” is only showing temporary, and I can not send messages for a few seconds; but not a total loss of connection like I was getting last week, where I’d literally lose visibility of everyone for anywhere from 5-20 minutes.

Has the root issue been identified? There may have been a patch note I missed. Just curious where this has ended up, thanks.