"Token request failed" after login, sync client doesn't work afterwards

[lukas-buergi]

Note: Please write your issue only in english

Description
I often get an error message token request failed in a pop up window when trying to log in to set up syncing with the desktop client. Happened both on Windows 11 and Debian.

Steps to reproduce
Steps to reproduce the behavior:

1. For some reason you are logged out, fresh computer, timeout/unknown reasons.
2. Try to log in.
3. Enter username, password. Confirm 2FA if necessary.
4. After all of the is completed successfully, there is a pop up windows token request failed and the client doesn't register it as a successful login.

Expected behavior
I'm supposed to be logged in and can choose what/how to sync.

Screenshots
If applicable, add screenshots to help explain your problem.

Logs
"Open debugging folder" in "Preferences"
We need you to enable "Extended Full Log" in "Debugging information"
Please note that the name of your files will appear in this log.

Additional context
Add any other context about the problem here.

[ClementKunz]

Hi @lukas-buergi ,
Thank you for your feedback.
Following a short service outage a few weeks ago, some apps have been disconnected. This disconnection has brought to light a bug making the reconnection impossible and sometimes leading to a crash.
This has been fixed in version 3.8.6.3 which is currently available on the beta release channel for macOS and Windows. If you are unable to update from the app (because of a crash, for example), you can download the Windows version here. Then, you must execute it from a cmd window with the following command: <path to the exe> /S /launch.
For the Linux version, you can download it from here and simply replace the previous appimage with the new one.
Regards