After playing around using postman I found the issue.

When sending a Bearer: "" or Bearer: "xxxxxx" token, the server returns "Authentication Required".

But when sending no Bearer token or an empty Bearer: it works fine.

So when logging in; no token must be supplied else it tries to authenticate against that token instead of correctly generating a new one provided you submitted valid credentials in the JSON body.

Seems a bit odd to me, but ok.

Every service like azure, github, google, etc implements OAuth2 but with modifications so you have to implement those modifications also in Qt.

Hi,

Since it's username/password your original clientGUI::provideAuthenication should have worked however I would not have read the content of the reply just called setUser and setPassword