Zwift freezing or crashing mid session

All, I had similar freezing problems about 12 months ago. Recently it had been fine up until the last version update (Friday) where upon all Ant+ connections dropped after 50 minutes.

A reboot returned the connections, however today after 15 minutes Zwift froze and crashed. I had to kill the session via task manager.


  1. I had a strong Wi-fi signal to my laptop with a 100 Mbps speed.
  2. There were over 6,800 users on Zwift at the time of the crash.
  3. I am using a Tacx Flux smart trainer.

Any suggestions welcome.

I find it interesting that these crashing issues on this thread all involve the Tacx “smart” trainers.

Anyway, sounds like you need to place a work ticket and send the log files to Zwift.


I looked but no find. Where is the Upload images setting?

Under the Menu, goto Settings → Image Loading. I’ve only used Windows 10, so I’m not sure if/where it is available on other platforms.

Thanks! I appreciate it!

UPDATE 1/14/2019: Zwift has been working perfectly since I purchased the Ant+ dongle with 6 foot cable. And disabled the Bluetooth sync for my Tacx Flux S Smart trainer.

So Zwift BlueTooth connect for the smart trainers is in BETA and it is the Bluetooth module that was crashing Zwift.

The BleWin10Lib.dll is the programming library for Bluetooth Low Energy and it is listed as the problem in the Problem signature in the Windows Error Report (see below).

(The Windows Error Report (WER) is in the in the ComputerSpecs.txt file in the Zwift file folder. And at the bottom of a very long text file you will find the WER. It states the ZwiftApp.exe is crashing and the problem is in the BleWin10Lib.dll programming file. In the WER log under Problem signature P1 is the app that is “crashing” and P4 is the app that is causing the App to crash)

By the way I figured this out, not Zwift IT. I sent all this info to them and they wrote back, “After looking at your Error logs it looks like your graphics driver is out of date. Please update the Driver.”

What is irritating was no where does it say in my logs that my video driver was to blame and I already had updated my graphics driver 5 days earlier.

I don’t think they looked at my Windows Error reporting files. I know they are busy but?

Anyway I hope this helps someone.

UPDATE1/10/2019 Had to put in here b/c only 3 consecutive replies allowed in this thread until someone else comments.

The update is, it wasn’t the SteelSeries engine. Today Zwift crashed 3 times in 30 minutes.

All the Zwift log files show the same ending line when it crashes and kickes me back to the desktop:
“Giant dt in app.=2.62” or some other .* number.

I have put in a work ticket with all the log files. I’ll update when I get a response.

Flux S smart trainer.
Windows 10
Core i7-8750H @ 2.20GHz RAM 16GB
GeForce GTX 1070 with Max-Q Design/PCIe/SSE2
OPENGL 3.1.0
Connecting with Bluetooth LE
This is basically what I see in the end of the log file after Zwift Crashes: It always ends with Giant dt in App.

"NETWORK:Delayed packet detected: Delay=382.82, Meters=107.8 networkID=613729, rider name=S

[6:27:20] FPS 71, 178899, 13027, -301700

[6:27:20] NETWORK:Delayed packet detected: Delay=485.14, Meters=96.3 networkID=1012207, rider name=S

[6:27:20] NETWORK:Delayed packet detected: Delay=439.59, Meters=199.8 networkID=331730, rider name=A

[6:27:20] NETWORK:Delayed packet detected: Delay=16.80, Meters=194.0 networkID=403196, rider name=J

[6:27:20] NETWORK:Delayed packet detected: Delay=0.00, Meters=131.1 networkID=74887, rider name=

[6:27:23] Giant dt in app. dt = 1.99"

In my ComputerSpecs.txt file it states the error is the


Windows Error Reporting:
+++ WER0 +++:
Fault bucket 1682281794336094508, type 4
Event Name: APPCRASH
Response: Not available
Cab Id: 0

Problem signature:
P1: ZwiftApp.exe
P3: 5c24c8ae
P4: BleWin10Lib.dll
P6: 5c1d8a45
P7: 80000003
P8: 000000000000208f

1 Like

Hi James,

Excellent answer.I have been experiencing the same problem.
Following your analysis, I also looked at my Windows Error Reporting overview and found a similar error message. See below.

FYI, I also have a Tacx smart trainer.

Windows Error Reporting:


Stopped working

‎1/‎15/‎2019 8:27 PM

Problem signature
Problem Event Name: APPCRASH
Application Name: ZwiftApp.exe
Application Version:
Application Timestamp: 5c24c8ae
Fault Module Name: BleWin10Lib.dll
Fault Module Version:
Fault Module Timestamp: 5c1d8a45
Exception Code: 80000003
Exception Offset: 000000000000208f
OS Version: 10.0.17134.

Additional Information 1: 35fc
Additional Information 2: 35fce49bba3d0f8d11b1e4018f7c348f
Additional Information 3: 93f7
Additional Information 4: 93f7c6bbbce3e277bde46227c923a726

Extra information about the problem
Bucket ID: 22d482ed114d1c49c758aa60fb82792c (1682281794336094508)

Zwift Log

[20:27:33] Giant dt in app. dt = 1.81

1 Like

Glad I was able to help. The Ant+ dongle with 6ft cable was the best $40 I have spent. I haven’t had a single crash since I got the dongle.

Only thing I will say is that the Tacx cadence sensor isn’t so accurate in the low end of the cassette (eg. 28 teeth and up) . It overestimates the cadence by up to 40 RPM’s. The higher gear of the cassette are much more in line with my real cadence.

It’s kinda funny b/c when this happens Zwift shows my Virtual self spinning like a madman. Zwift is doing a great job with the graphics and handling all those riders and their data. I have seen up to 12,000 online at a time. That’s a lot of data.
They just need to work out the BlueTooth bugs.
Ride on!

I usually don’t comment once I’ve found and fixed my problem…but I wanted to say that doing the clean boot fixed my issue, which was that the app was crashing about 20 minutes into my training sessions, every time.

It was very frustrating, but fixed now.



James outstanding detail. It’s helped a lot.

The similarities I see are windows 10 and a Tacx hardware and full screen. I have the Neo 2. The Neo 2 and Flux 2 are experiencing cadence issues. Tacx is working on that.

I was dropped 2.1km from the end of Stage 6. (Climbing is my weak spot).

I’ve only switched to full screen in the past week or 2 so I’ll switch back to windowed and give that a go.

My setup:
Tacx Neo 2 for Power and Control.
Garmin Ant+ cadence because the Neo is stuck at 0 RPM till they fix the Neo 2 and Flux 2. (About 50% of owners.)
I7 64G Ram
I’ve tried both WiFi and hardwired
WFi 600mbps
Hardware 1Gb
Internet 300mbps
Viiiiva HRM

I’ll also try switching of BTLE on both the PC and the Neo.

Thanks all for sharing.

Ride On!!

Thanks I have this issue again too. I did switch to full screen so I’ll switch back. My taco neo hasn’t been finding the Ant so I also switched to Bluetooth.
The last two weeks I’ve been tossed off a lot and this morning 3 times.
I did a full uninstall and reinstall which helped last week but not again today.

I was wondering where do you connect the ant extender to the neo trainer? I don’t see a place to plug it in???

I’ll get one today and try that. I was going to take my laptop in but maybe this will help instead.

Ok I’m getting the network delayed packet detected message often from today…is this not a network issue??? Our wifi has been sketchy of late but if a dongle may fix that I’ll try it for sure.
Help??? Support at Zwift taking many days too long. Thanks

The Ant+ extender is just a USB cable that plugs into your computer. The Ant+ dongle goes at the end of the USB cable and you place the dongle on the floor within 12 inches of the smart trainer out of the way so you don’t step on it.

You will have to disconnect from the BlueTooth on your computer. I just turned mine off in the in the Devices and Printers section of Windows 10. Just click off then Log back into Zwift and it should automatically find your Trainer with the Ant+ and connect.
The Bluetooth for the Zwift is in BETA testing and doesn’t have all the bugs worked out so it is crashing your program most likely but I would have to see your Windows Error reporting file to known for sure.
Yes I had a long wait for Zwift support so I figured it out myself what was going on and then just bought the Ant+ dongle and extender cable.
I hope this helps.

Thanks yes I googled it and noticed it just hangs on thanks !

So I guess I won’t be able to use heart rate on the program just on my watch as is Polar BLE. That’s ok I actually just started using it last weekend on Bluetooth so maybe that’s in the way too.

The other thing I had done was full screen and higher resolution in last few days so I’ve disabled all that.

Thanks I’ve ordered the cable and thanks to amazon prime it’ll be here soon :slight_smile:

I’m also going to put my computer laptop on an open air stand so it can stay temperate.

Hopefully one of these things fixes it. And I don’t doubt that Zwift has major stability issues with the quadrupling of riders they’ve signed on.

People getting really peeved!!!

Appreciate the reply.

Oh one more thing… can I keep my Bluetooth on on computer but just use the Ant option on Zwift pairing. I gives me both options to choose. As well as trainer connecting via TACX ant.

My wife had the same HR monitor that was BT and it wouldn’t connect to Zwift or the Garmin so she switched to the Ant+ HR strap from Garmin and it worked perfectly.

Regarding turning back on BT, when I turned off the BlueTooth on my computer once Zwift connected to my trainer with the Ant+ dongle it then automatically turned on the Bluetooth again and then later connected to my iPhone Zwift companion app. Every time I have logged back onto Zwift it has always reconnected with the Ant+ dongle as the default. So yes you can turn on the BT after Zwift has connected with the Tacx trainer with the Ant+. it should always connect with the Ant+ dongle from then on and BT can stay on too. I haven’t had to mess with anything at all. It has worked perfectly.

One thing about BT is it only allows one connection at a time so you may have a problem with trying to connect your Heart Rate monitor if you also use the Zwift companion app. as both use BT. Ant+, however, allows endless connections.
I would just by an Ant+ heart rate strap. My wife just bought a Garmin one for a friend from Amazon for $56.40
Here’s the link:
Let me know how it goes.

Thanks again…
So far I’ve been able to connect all things at one time BUT my app would flipnon and off or sometimes not go on at all so maybe that was an issue too. Bothers me less than the whole frigging ride crashing !!!

Re the monitor…Ugh I’ve spent so much trying to fix these issues plus I also just got an external monitor to improve the experience!!

But I think this is a sign cuz I’m at my gym and up comes an add for the member offers we get for various places including Garmin :):slight_smile:

I’m Canadian so different Amazon site too and yes I’ve seen them.

Will check it out.

Thanks again. I’ll let you know tomorrow if my dongle cord works plus all the other fiddling I’ve done!

It’s stressing me out :frowning:.


Well the Tacx trainer is one unit that sends the BT signal to your computer. That one unit though has a Power Meter, Cadence sensor (somewhat inaccurate), and speed sensor, and sends all that info over ONE BT signal. So if you have a Heart rate monitor with a separate BT signal you would technically have to connect either the HR monitor or the Tacx trainer but not both. You could try to connect your Yahoo BT HR monitor through the bluetooth to Zwift to see if it works for giggles (it should) but you shouldn’t be able to connect your smart trainer at the same time.

Yes it is frustrating I know. That is why I am trying to help on this forum b/c I didn’t get any useful help from Zwift. maybe they are just overwhelmed and do not have anyone trained in programming or connections regarding the BT. All my inquiries regarding the BTLE connections have gone unanswered by Zwift.

Did you buy the Ant+ dongle? and stop using the BT to connect to your trainer and did it fix your problem?
Glad I could help.

Buying the Ant+ dongle and 6 foot cable extension would be my suggestion. I bought the one on Zwift for $40 and it arrived at my house in 3 days.
Did you buy the dongle and did it fix your issue?