Answer from Pioneer:
Spotify no longer supports his LibSpotify service, which was implemented in the N-50A.
More information can be found through their link:
https://support.spotify.com/us/article/why-cant-i-use-the-spotify-app-on-my-speaker/
(Not every model infected by this inconvenience is listed on the website)
They also suggest a couple of solutions which might help you further.
F.e.:
• Use Airplay for transmission if you have iOS equipment.
• Use Bluetooth for transmission if you have Bluetooth equipment
• Connect SMART TV or game via HDMI if these equipment supports Spotify
It will unfortunately not be possible to provide a firmware solution regarding this issue, given that this feature will be fully stopped by Spotify.
The problem only affects older Pioneer models, more recent models will be out of the clear.
Given that Spotify is a third party content, their services may be changed, suspended, interrupted, or discontinued at any time without notice, and Pioneer disclaims any liability in connection with such occurrences.
Pioneer does not represent or warrant that content services will continue to be provided or available for a particular period of time, and any such warranty, express or implied, is disclaimed.
We would like to apologize, but unfortunately there is not a lot we can do regarding this discontinued feature. We merely offer the possibility to use third party features, but can not be held accountable if one of these features are stopped by the company in charge.
Best regards