iPhone 5 or earlier iOS 9.3.5 cannot download older versions of apps

[unclebob101]

So, I’ve got an old iPhone 4s on 9.3.5 that I mainly use as a compact music device. It can download any apps older version if the current up-to-date version of the app in the store is below iOS 11. When app requires iOS 11 or above there is no “download older version of this app”. Instead there’s just a popup saying “unable to purchase, app is not compatible with this iPhone”.

Is this some sort of bug or when the developers update their apps to work on devices above iOS 10 it automatically wipes all the old versions?

 

[now i see it]

it's not a bug, but "progress".
Some app developers (the nice ones) will keep older versions available to download if your device isn't running a more current OS. Other developers say "screw you" and kill off the earlier versions, only allowing the most recent version to be downloaded. Bank apps are notorious for this.

Most apps aren't really "necessary" things to have, but "wants". If you find that there are too many apps that you want but can't download because you're stuck on iOS 9, the only choice is to buy a more current iPhone. My recommendation would be to buy a used iPhone 5S. It'll run iOS 12. The iPhone 5 will run iOS 10.

 

[pika2000]

Even some apps no longer provide compatible versions for iOS10/32-bit devices. My iPhone 5 is pretty much obsolete.
If you want cheapest iPhone, at least get the 5S. It's iOS11+ compatible and 64bit. Eg. Safari extensions like ad-blockers are only for 64bit devices.

 

[NoBoMac]

How are you selecting apps? If you had previously "purchased" an app, you should be able to re-install the old version from the Purchased list in App Store.

But otherwise, yes, developers might kill off old versions. Any new app updates are required to be using 64-bit APIs, so no incentive for developer to keep the old around. Apple does some culling of their own, when they see/think an app is abandoned.

 

[AstonSmith]

If you had previously "purchased" an app, you should be able to re-install the old version from the Purchased list in App Store.

Yes, that's the key to this.

If you use a computer with iTunes to purchase the app you want (even for free), it will then show up in the 4S's Purchased list. If you attempt to install it from there, it will complain that the latest version is incompatible but allow you to install the last available version that will work (if there is one).

Note that even after installing an old version of an app, it still might not work if it uses the Internet in some way. e.g. a weather app might effectively block old apps by not providing weather data when they're below a certain version number.