App consequences of Windows 10 Mobile
One of the overlooked disadvantages of upgrading from one mobile OS version to another, regardless if you are using iOS, Android, or Windows Phone, is the possibility that your apps are no longer supported on the newer mobile OS version (or mobile device). For example, the free version of Bookman for iOS works on an iPod Touch 4th generation, but no free version is available for iOS9.
One of the consequences of Windows 10 Mobile is that apps that worked fine with Windows Phone 8.1, are no longer tagged as available for Windows Phone 8.1 users even though the apps still work. Apps that fall in this category can no longer be reinstalled if you performed a fresh reset of your Lumia or Windows Phone device. This can happen if developers have either made changes to the app specifically for Windows 10 Mobile, removed the app from Microsoft Store altogether, or Microsoft Store deems it for Windows 10 Mobile only even if the app works in Windows Phone 8.1.
Some of the apps I can no longer install on my Lumia 925 after a device reset are the following:
3. Windows Phone Insider
4. Lumia Video Trimmer
5. The Guardian news app
7. Babbel Learn French
8. Code Scanner
9. BBC Radio Streams
Note: All of the apps were working as designed in Windows Phone 8.1 prior to the device reset. The Lumia 925 is not eligible for Windows 10 Mobile.