https://www.theregister.co.uk/2017/10/11/sonos_privacy_speakers/
Sonos updated their private policy to allow the company to gather much more info from you and your use of their devices, even how you use Alexa to control them. Some people refused, which stopped their ability to install firmware updates. Fine. Then the apps on their phones were updated either manually or using the automatic updates feature of their phones, and the new app version won't work with the old firmware. So, either they have to accept the new privacy policy, or they cannot use their phones to control or configure their Sonos devices.
Sonos updated their private policy to allow the company to gather much more info from you and your use of their devices, even how you use Alexa to control them. Some people refused, which stopped their ability to install firmware updates. Fine. Then the apps on their phones were updated either manually or using the automatic updates feature of their phones, and the new app version won't work with the old firmware. So, either they have to accept the new privacy policy, or they cannot use their phones to control or configure their Sonos devices.