Just to complete our analysis :
- did both user reconnect and clean cache after migration ?
The "other" user had not connected to ProjeQtor quite a while before the upgrade. So she was not logged in and the browser cache probably had been purged automatically. However, none of the users purged the browser cache explicitly.
The admin logged in to let ProjeQtor perform the upgrade, however the browser was used with a third user account before (which was not involved in what happened then).
- did "other" connected as admin before, with same browser session (not closing browser) ?
No, admin and the other user used completely different computers, which makes it even more strange.
(Otherwise I's assumed some confusion with the local browser session or cookies or something...)
- did admin change some "global" settings ?
- do you remember which settings you changed before uploading profile image ?
Sorry, I don't know - admin probably changed global settings after the upgrade, but I don't know how the timing was relative to the actions performed by the other user.
She logged in after the update was finished and, besides other changes, changed the language from German to English. This caused ProjeQtor to briefly show the login screen again, and to auto-relogin, if I remember correctly.
This must have been shortly after the admin uploaded his profile image.