I have noticed if site/accounts/* does not have write permission, you get an error “Invalid API Method” when trying to change your password in the Panel. Seems like a more appropriate error should be shown.
How about creating an issue in the panel repo at GitHub?
Created an issue on GitHub: https://github.com/getkirby/panel/issues/583
I already did (https://github.com/getkirby/panel/issues/569) and it was closed.
Sorry, completely missed that. I guess it’ll be solved with the upcoming 2.2 then.