Can't launch Zwift errors 400 403 404? [April 2021] [SOLVED]

Clear cookies and cache from Microsoft Edge worked for me! Thanks

Thanks @Ashley_Evans! Installing the free version of ccleaner and letting it do a default cleaning resolved this not launching on my Win10 machine. I had tried restarting, uninstalling, clearing my IE cache, deleting & re-adding my wireless network, etc. and nothing worked until I ran ccleaner.

@shooj
After several unsuccessful attempts of uninstall, installing, clearing brower history/cache/cookies of IE and Edge on my Win10 machine: still having this issue.
I am not using, but still installed is Internet Explorer version 20H2 (Build 19042.928) and followed also step no 3 of your initial description. Please fix this issue.
I do not receive any error, it just crashs after this step:

@shooj
There seems to be an issue with custom workouts since the recent 2021-04 update. As stated above Zwift crashed during the login process. See this example of logfile excerpt:

[12:28:44] NETCLIENT:[INFO] Analytics ID: a54203f8-7eea-46f6-b5c0-82c4e47997de
[12:28:44] NETCLIENT:[INFO] TCP host 52.33.59.1:3023
[12:28:44] NETCLIENT:[INFO] Connecting to TCP server...
[12:28:44] CrashHandler: Dump Request Failed
[12:28:46] NETCLIENT:[INFO] Saying hello to TCP server (largest wa is 0)
[12:28:46] CrashHandler: crash detected: 9944
[12:28:46] CrashHandler: Dump Meta complete
[12:28:47] NETCLIENT:[INFO] UDP host 18.237.214.72:3022
[12:28:47] NETCLIENT:[INFO] Connecting to UDP server...

If deleting the “Workouts”-folder, Zwift starts correctly and downloads all workouts again / sync with other devices. While in previous versions obviously custom workouts with comments only were accepted/tolerated, this seems to be an issue with this release (i.e.: I have had 2 files causing no harm during the last month and updates, which are not intended as workouts, but contain some remarks only; one with correct syntax (, the other not)). I have removed these two files from the custom workout library and without these a login is successful.

However, the issue remains (ie. Zwift crashs) if adding just one single, correct workout to the existing library. For your reference, due several renaming of my workout library the workouts.files contains actually 542 deleted workouts already.

Hope to support you and and others by sharing this info.

Everyone - wanted to update you on this issue.

Though it seems related, this is not a problem caused by any particular version of the Zwift game app. It’s a complex server-side issue that we’ve been working on solving. The incidence of this issue has dramatically been reduced since first spotted, but a few are still happening.

I will update this thread when it’s fully resolved.

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2 posts were merged into an existing topic: Recent Zwift update (May 6th.) Apple users can’t log into the game

This is so frustrating. Took me an hour to get to work last time and now it’s happening all over again. I’ve done all the recommendations and still no joy

I was having the same issue running Zwift on MacOS Big Sur 11.2.3 and turning off WiFi before launching Zwift seems to be the workaround for me. Phew.

Issue still persists for me. Turning off WiFi on my Win10 PC results in expected warning after launching Zwift that no WiFi signal is present (Zwift Error ZL01) - v1.12.1

Having the same issue today. Zwift was working fine as of last night. At first a error 400 was displayed. After restarting I now only see a “something is wrong, please close and restart zwift.” Or something to that affect. Three restarts with no change. Giving up on zwifr for now.

Loads of errors getting in tonight, and a crash between Giant crit races. Not great.

Oh and I had to log in again after the game loaded.

@Dave_ZPCMR
Is it the same 400 / 403 errors?
Tell me particulars about the crash: when did it occur? What device & OS were you running at the time?

I’ll create a thread for the crash, it’s repeatable

400 error was different, a pop up on the launcher with an OK button. Socket error. The launcher itself kept saying try restarting Zwift. Took several attempts to get in.

I had this issue over the last week or so. I used @Dave_ZPCMR 's workaround of deleting browsing history, seems to work ok so far.

Windows 10, recent gaming desktop. Got the ‘Something went wrong.’ message.

Hello,

I have the issue on Mac 11.3.1 MacBook Pro 2014. Safari Version 14.1 (16611.1.21.161.6). I tried the debugging steps. I am able to launch it by turning off WiFi then turning it back on once I get to the login page.

This needs sorting once and for all, guys. :wink:

It will no longer appear on consumer versions of Windows 10 after June 2022, Microsoft wrote in a blog.

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A post was merged into an existing topic: macOS problems with new update? [1.13.0] [May 19 2021]

ZWIFT: Please put a BIG NOTE on the front of your website telling us about this, I spent an hour trying to fix this , only to realise its on your side not mine. Off I go to Trainer Road until i hear from you.

UPDATE May 24

We made some changes on the game server that have reduced the lingering instances of the 403 error to almost zero. This issue was not tied to what game version you’re using FYI.

If you are still experiencing the 400 / 403 / 404 errors at log-in, please check in with us on this thread. Otherwise, we’ll mark this thread Solved.

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