This is covered in the forum, release notices, docs, and Duplicati. Stable is actually quite new, but before the first one recently, the Beta version was the best-tested. Canary is always an initial view.
I keep asking for the download page to say something about the important changes, including new password requirement. If you never had one before, you need one now. Here’s the release notice:
Or if you prefer the forum announcement (which accepts comments – especially handy for Canary users to see what’s right or wrong with a given one – as noted, these are initial release for testing):
The mandatory password is detailed (but could always use more details) in the documentation:
This is also linked from the login screen in case someone gets surprised by the password need.
For brand new users, it’s first run. For existing users, it comes up to make it easy to set password.
If you missed that opportunity, you can get in password-free from the TrayIcon, then use Settings screen to put on a password in case you ever like to directly browse in with a URL or a bookmark.
Not really IMO, but notification of users could be better, and the original problem IMO is not from Duplicati itself, but from an error in how the update is being directed. Here are some references:
@kenkendk any chance the manifest files could get fixed soon to avoid confusing more users?
EDIT 1:
I’ll concede that seeing a popup titled “First run setup” could be worrisome to a current user, but content should make it clear what it’s trying to do. It repeats some of what I said above. The text:
Duplicati needs to be secured with a passphrase and a random passphrase has been generated for you.\nIf you open Duplicati from the tray icon, you do not need a passphrase, but if you plan to open it from another location you need to set a passphrase you know.\nDo you want to set a passphrase now?
This popup is not shown if a password already exists, but I’d guess most previous users lack one.
I’d agree with this topic’s title saying “Duplicati versions install mess up”, and hope it will get fixed.