Spotify Plug-in authorize button not working

I’ve just updated my Volumio to latest version (2.799 ) then installed the Spotify plug-in. I am able to log in to my spotify Premium account but when I press the “Authorize” button in the settings section of the plug-in there is no further action, i.e. no authorization takes place.
Please advise.
My system is a Raspberry Pi B with an external USB DAC

Try again later to see if it is a problem at Spotify’s end. I have validated successfully a couple of times recently.

Edit: just tried a fresh installation of Spotify plugin on 2.799. Validation worked fine.

Rebooted Volumio. Uninstalled, then reinstalled Spotify plug-in and all is well