error with localisation activated

[nilsbehlen]

when localisation is activated and this provider is the only one in the flow, when trying to change the language from the dropdown, an error occurs.

[lukasmatusiewicz]

Problem: LoginFormsProvider is grabbing the wrong "base URL" from the request context on the initial challenge. The correct base is the internal flow endpoint /login-actions/authenticate, but it's defaulting to the OIDC endpoint /protocol/openid-connect/auth.

Manual language change (by user) adds kc_locale=de param to the end of the link. This doesn't fit to this endpoint and the page is simply reloaded. Since the request endpoint is changed after some user's move (e.g. submitting empty form), the endpoint changes, and addition of the kc_locale become possible.

It shouldn't be kc config issue - 90%.

Check how to fix the code, to build the right URI already at the first step: authenticate(AuthenticationFlowContext context).