Chatty zwift log file

Bugs and Support
1

My hard drive filled up while having Zwift running in the configuration screen (for pairing sensors).

I realized that it is the zwift log folder (C:\Users\\Documents\Zwift\Logs) that is causing the issue. The current log file was 38 Gb! I deleted it because I wont be able to open and read it anyway.

However I looked into one of the older log files that zwift automatically renames after a while.
I noticed that this file increases with 2 Gb every 4 minutes because of lines looking like this: “[ERROR] LAN Exercise Device: Error receiving answer from AAA.BBB.CCC.DDD ({372176) [10009] Den angivna filreferensen är ogiltig.”

The AAA.BBB.CCC.DDD denotes various local ip adresses and I edited them out for this post.

I see that there are lines like “Skipped 11 repeated messages.” but I would prefer this to include many more similar lines so the log file does not become so big.

2

(post deleted by author)

3

Thanks for reporting @Daniel_Karlsson - we’re looking into this.

4

That reminds me, I need to delete the 1,800 screenshots that Zwift automatically saves to the app folder on iOS. That cleared up about 1GB of space.

5

Is this what makes up the 1.52 GB in ‘Documents and Data’ related to Zwift on my iPad? If so, how do I clean that up?

6

What files should be cleared from time to time?

7

I don’t know. I use iMazing to get access to the files on my iPad and from there I can go into the Apps/Zwift program folder. Zwift saves it’s automatic screenshots to the root app folder (doesn’t even put them into a separate folder, just raw-dogging them into the app folder) so I delete all of those. There’s an activities folder there too which is where Zwift saves all the .fit files. I’ve got about 2200 of them since 2022 but they only take up about 120mb of space so I will leave them alone for now.

I guess, if you delete Zwift off your iPad and reinstall it then it will clean up all those files as part of the process (because they are in the app folder) but I don’t want to download the 3GB of actual program files again.

8

In one second, Zwift adds 93000 lines to the log file.

Note that the resolution of time stamps in the file is only 1 second, so it is not very relevant with much more than 1 message per second.

9

Any update on this? I just checked my log directory to diagnose a different issue and noticed I have 19GBs of logs. Zwift is effectively reducing the lifetime of my SSD by writing 3 Megabytes/second! It seems the logs started to get out of hand around the 8th of January as that’s the earliest a log file surpassed 1GB in size:

total 19G
drwxr-xr-x 2 kyle kyle 4.0K Jan 16 16:35 .
drwxr-xr-x 4 kyle kyle 4.0K Oct 8 10:28 ..
-rw-r–r-- 1 kyle kyle 1.4K Jan 15 19:26 ‘Launcher_log (old 1).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 15 17:05 ‘Launcher_log (old 2).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 15 10:48 ‘Launcher_log (old 3).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 14 20:31 ‘Launcher_log (old 4).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 13 19:53 ‘Launcher_log (old 5).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 12 19:36 ‘Launcher_log (old 6).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 10 20:28 ‘Launcher_log (old 7).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 10 20:05 ‘Launcher_log (old 8).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 8 19:46 ‘Launcher_log (old 9).txt’
-rw-r–r-- 1 kyle kyle 1.4K Jan 16 16:35 Launcher_log.txt
-rw-r–r-- 1 kyle kyle 7.2G Jan 15 21:14 Log.txt
-rw-r–r-- 1 kyle kyle 1.4M Jan 15 17:14 ‘Log (old 2).txt’
-rw-r–r-- 1 kyle kyle 318M Jan 15 10:54 ‘Log (old 3).txt’
-rw-r–r-- 1 kyle kyle 49M Jan 14 21:17 ‘Log (old 4).txt’
-rw-r–r-- 1 kyle kyle 1.9G Jan 13 20:56 ‘Log (old 5).txt’
-rw-r–r-- 1 kyle kyle 2.9G Jan 12 21:08 ‘Log (old 6).txt’
-rw-r–r-- 1 kyle kyle 21M Jan 10 21:38 ‘Log (old 7).txt’
-rw-r–r-- 1 kyle kyle 4.4G Jan 10 20:27 ‘Log (old 8).txt’
-rw-r–r-- 1 kyle kyle 1.7G Jan 8 21:41 ‘Log (old 9).txt’

The logs are the same as what was reported in the OP, just a flood of (literally thousands of these logs a second):

[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.18.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.16.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.30.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 192.168.86.160 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.18.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.16.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.30.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.18.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.16.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 172.30.0.1 ({000000) [10009] Invalid file handle.
[21:38:09] [ERROR] LAN Exercise Device: Error receiving answer from 192.168.86.160 ({000000) [10009] Invalid file handle.
[21:38:09] Skipped 1 repeated messages.

EDIT:

Upon further testing I’ve noticed that these logs only appear while on the pairing screen and stop once I get to the main menu of the game. I often start Zwift right before I get my kids ready for bed so I don’t have to wait for the game to load (which takes a while). The game can sometimes sit there for an hour, which explains my massive log size. Even still, sitting at the pairing screen shouldn’t thrash the users SSD.

10

My oldest log file of this size is from 6th Dec 2025. It was recorded with
Game Version: 1.103.0(156100) rc/1.103.0

Latest log file was recorded with
Game Version: 1.104.4 (157262) rc/1.104.4

shooj (Shuji) 11

Hey gang - we’ve got a fix coming for this in game version 1.106. Thanks for flagging this up to us!

4 Likes
12

Opened Zwift yesterday AM. Went to ride. Something came up and didn’t. Closed Zwift 10 hours later. Today find C drive full. 1.1TB. Found this forum and deleted the file. :slight_smile:

13

which file did you delete? Is it just looking for the biggest one?

14

I did use a utility program (wiztree?) to find the biggest file before I knew it was zwift, Drive is 1.8TB and has less than .3 TB on it normally, so file was massive. Easy to spot. Once I found it I searched the web for what it was and found it was Zwift, then deleted.

15

Thanks. Yes, I see in the Zwift files a great big one. I am going to try the update first and see if that corrects it. And if not, then delete it.

EDIT: The update removed the huge file for me.