Reading user library works for one account but not others

[alangap]

Plan

Free, Premium

Country

United Kingdom

Device

iPhone 12, iPhone SE, Dell Laptop

Operating System

Windows 10, iOS

My Question or Issue

I have developed a Django-based web app where the user logs in and the app displays saved songs. It works perfectly well when I use my account, however the endpoint 'https://api.spotify.com/v1/me/tracks/' returns a 403 error when testing the app on other accounts/devices.

I have tried multiple accounts (free and premium) on multiple devices (Windows laptop, iPhone etc) so I don't believe it's a software/hardware compatibility issue - any thoughts/info/advice would be appreciated.

[Ximzend]

I think you are expecting this issue, because your app is still in Developer Mode. You need to add the accounts you want to test your app with first to make it work. How to do this, you can find on the following page: https://developer.spotify.com/documentation/web-api/guides/development-extended-quota-modes/