thanks for your quick reply.
I did not have to setup a new password during the signup process. By clicking the G+ logo I had to select my google account (I have two associated with my google chrome), and was signed up without setting up a password. It uses the one I am already logged in with in my browser.
Also logging into MyVolumio I just click on the G+ logo and don’t enter a password since I am already logged into Google with my browser. The login should receive a valid token from Google.
I expect on the volumio.local website the same procedure where I can click on such a G+ logo to login without entering a password on the volumio.local website itself, since it receives the Google token.
As you suggested I changed the password in the MyVolumio profile. And now I can login. Thanks!
Maybe my google password contains illegal characters according to your desired format. It works now, but I think it doesn’t completely follow the standard federated authentication routine, at least not in volumio.local.
Anyway, works for me now so I’m happy.
Thanks for your great work on Volumio!